Added or improved rendering of many NHD features.

Based on Kevin Kenny's TopOSM-NY work, this adds improved rendering of
several features in NHD:

- Labels on area-based linear features (such as larger rivers)
- Foreshores
- Submerged rocks
- Submerged streams
- Inundation areas
- Hazard zones
- Special use zones
- Rapids
- Dams
- Non-earthen shores
- Water wells
- Springs
- Sinks
- Rises
- Gaging stations
- Water tunnels

The style files are also a bit cleaner by using entities from
include/nhdfcodes.inc, rather than specifying NHD FCODEs directly.

.gitignore

@@ -11,4 +11,5 @@ include/*.inc
 *.pyc
 errors.log
 geodata
-tile
+tile
+temp

README.md

@@ -131,8 +131,6 @@ To render a PDF, use renderToPdf() in toposm.py
 
 ## Credits ##
 
-Created by Lars Ahlzen (lars@ahlzen.com), with contributions from Ian Dees (hosting,
-rendering and troubleshooting), Phil Gold, Kevin Kenny (patches and style improvements),
-Yves Cainaud (legend), Richard Weait (shield graphics) and others.
+Created by Lars Ahlzen (lars@ahlzen.com), with contributions from Ian Dees (hosting, rendering and troubleshooting), Phil Gold (patches and style improvements), Kevin Kenny (improved NHD rendering, misc patches), Yves Cainaud (legend), Richard Weait (shield graphics) and others.
 
 License: GPLv2