Added a new config file parser.

The new config file parser has an interface that's nearly identical to
the OptionParser of optparse.

Below is a sample settings.py config file:

$ cat settings.py
import multiprocessing

if 'rendermode' not in locals():
    rendermode="lighting"

cachedir = "cache.%s.cachedir" % rendermode

procs = multiprocessing.cpu_count() - 1

gmap.py

@@ -22,7 +22,7 @@ if not (sys.version_info[0] == 2 and sys.version_info[1] >= 6):
 
 import os
 import os.path
-from optparse import OptionParser
+from configParser import ConfigOptionParser
 import re
 import multiprocessing
 import time
@@ -43,20 +43,20 @@ def main():
         cpus = multiprocessing.cpu_count()
     except NotImplementedError:
         cpus = 1
-    parser = OptionParser(usage=helptext)
+    parser = ConfigOptionParser(usage=helptext, config="settings.py")
     parser.add_option("-p", "--processes", dest="procs", help="How many worker processes to start. Default %s" % cpus, default=cpus, action="store", type="int")
     parser.add_option("-z", "--zoom", dest="zoom", help="Sets the zoom level manually instead of calculating it. This can be useful if you have outlier chunks that make your world too big. This value will make the highest zoom level contain (2**ZOOM)^2 tiles", action="store", type="int")
-    parser.add_option("-d", "--delete", dest="delete", help="Clear all caches. Next time you render your world, it will have to start completely over again. This is probably not a good idea for large worlds. Use this if you change texture packs and want to re-render everything.", action="store_true")
+    parser.add_option("-d", "--delete", dest="delete", help="Clear all caches. Next time you render your world, it will have to start completely over again. This is probably not a good idea for large worlds. Use this if you change texture packs and want to re-render everything.", action="store_true", commandLineOnly=True)
     parser.add_option("--cachedir", dest="cachedir", help="Sets the directory where the Overviewer will save chunk images, which is an intermediate step before the tiles are generated. You must use the same directory each time to gain any benefit from the cache. If not set, this defaults to your world directory.")
     parser.add_option("--chunklist", dest="chunklist", help="A file containing, on each line, a path to a chunkfile to update. Instead of scanning the world directory for chunks, it will just use this list. Normal caching rules still apply.")
-    parser.add_option("--lighting", dest="lighting", help="Renders shadows using light data from each chunk.", action="store_true")
-    parser.add_option("--night", dest="night", help="Renders shadows using light data from each chunk, as if it were night. Implies --lighting.", action="store_true")
-    parser.add_option("--spawn", dest="spawn", help="Renders shadows using light data from each chunk, as if it were night, while also highlighting areas that are dark enough to spawn mobs. Implies --lighting and --night.", action="store_true")
+    parser.add_option("--rendermode", dest="rendermode", help="Specifies the render type: normal (default), lighting, night, or spawn.", type="choice", choices=["normal", "lighting", "night", "spawn"], required=True, default="normal")
     parser.add_option("--imgformat", dest="imgformat", help="The image output format to use. Currently supported: png(default), jpg. NOTE: png will always be used as the intermediate image format.")
     parser.add_option("--optimize-img", dest="optimizeimg", help="If using png, perform image file size optimizations on the output. Specify 1 for pngcrush, 2 for pngcrush+optipng+advdef. This may double (or more) render times, but will produce up to 30% smaller images. NOTE: requires corresponding programs in $PATH or %PATH%")
     parser.add_option("-q", "--quiet", dest="quiet", action="count", default=0, help="Print less output. You can specify this option multiple times.")
     parser.add_option("-v", "--verbose", dest="verbose", action="count", default=0, help="Print more output. You can specify this option multiple times.")
     parser.add_option("--skip-js", dest="skipjs", action="store_true", help="Don't output marker.js or regions.js")
+    parser.add_option("--display-config", dest="display_config", action="store_true", help="Display the configuration parameters, but don't render the map", commandLineOnly=True)
+    #parser.add_option("--write-config", dest="write_config", action="store_true", help="Writes out a sample config file", commandLineOnly=True)
 
     options, args = parser.parse_args()
 
@@ -87,6 +87,11 @@ def main():
         parser.error("Where do you want to save the tiles?")
 
     destdir = args[1]
+    if options.display_config:
+        # just display the config file and exit
+        parser.display_config()
+        sys.exit(0)
+
 
     if options.delete:
         return delete_all(cachedir, destdir)
@@ -124,7 +129,7 @@ def main():
         logging.info("Notice: Not using biome data for tinting")
 
     # First generate the world's chunk images
-    w = world.WorldRenderer(worlddir, cachedir, chunklist=chunklist, lighting=options.lighting, night=options.night, spawn=options.spawn, useBiomeData=useBiomeData)
+    w = world.WorldRenderer(worlddir, cachedir, chunklist=chunklist, rendermode=options.rendermode, useBiomeData=useBiomeData)
 
     w.go(options.procs)