Add .gitignore
Add syntax definition for TableGen (.td) files.
Updates to TableGen.

- Added a new common class; Intrinsic
- Added a new storage type; signed
- Removed the IR global variable syntax.
- Simplified the expression for variables.
- Added an expression to handle ${var} syntax in strings.
Add default .sublime-setings file for LLVM
Fix a complex recursive pattern matching issue in TableGen.

- Greater-Than and Less-Than chars inside code fragments could erroneously be parsed as part of a Template.
- This patch makes it not possible to highlight templates within code fragments.
Reorder the recursive syntax highlighting to allow code fragments to appear outside of templates, and allow recursive templates.

- Now only code fragments are the special case: they may not include templates or nested code fragments.
Merge pull request #1 from parasyte/master

Add preliminary support for TableGen (.td) syntax highlighting