Whitespace, 80-col violations.
Add TOOL_VERSION_* macros to 'cabal_macros.h'.

Fixes #1547. Sample generated file: https://gist.github.com/23Skidoo/7026016
Docs for TOOL_VERSION_*.
Cosmetic fix.
Merge pull request #1549 from 23Skidoo/tool-version

Add TOOL_VERSION_* macros to 'cabal_macros.h'.