LLVM developer Vim scripts.

Settings for the Vim editor to work on llvm *.ll and tablegen *.td files.

Make targets:

• all: to fetch the latest files from the LLVM SVN.
• clean: remove all files that can be downloaded from LLVM SVN.
• distclean: same as clean, but does not remove Vim configs.
• install: install configuration. TBD.