rdmd: Use shell escaping functions from std.process

I've submitted them for inclusion into Phobos a while ago.
rdmd: Fix building library files (Issue 6535)
rdmd: Add some heuristics for detecting updated libraries (issue 6431)
rdmd: Include root module in deps freshness check (Issue 9508)
.gitignore: Windows binaries
Merge pull request #51 from CyberShadow/rdmd-fixes-20130310

rdmd fixes 20130310