Merge pull request #267 from SublimeText/master

Reset mbuilder to master
Capture output/errors in makePDF
Very preliminary makePDF revamp
First working example: SimpleBuilder
Fix display of errors and warnings
Sketch of preferences file
Revamping preferences file (not operational)
Fix SimpleBuilder so it works on Windows
New-style objs in AbstractBuilder; prefs fix
Bibtex/natbib handling in SimpleBuilder
Attempt at autoloading builders (NOT WORKING)
Attempt at autoloading builders (NOT WORKING)
Get SimpleBuilder to load and run from builders dir
Read texpath from preferences, not sublime-build file
Find out platform once and for all in makePDF
Fixed importing pdfBuilder in builders
Support for custom builders
Tweak preferences
Cleanup pdfBuilder
Fixups and traditonal builder