Adding Mac OS X .DS_Store files to .gitignore
reorganizing extension directories again
reorganization of extension directories
updated less makefile to build css files in the root src directory (t…
…o fix relative path issues). added output css files to root .gitignore
Add .gitignore file to ignore Thumbs.db files, making 'git status' less
noisy on Windows. We can easily add to this file to exclude additional
types of OS-generated / cruft files later.