Update docs to refer to correct option lua_omni_blacklist
Provide option to inspect omni completion module loading list

When set, the lua_safe_omni_modules option restricts the modules
to be loaded for omni completion to the standard Lua modules.
A list of modules that would have been loaded if this option was
not set can be used to track down modules having side effects
while loading by iteratively refining lua_omni_blacklist.
Update to Lua 5.2 keywords and standard libraries
Merge pull request #29: Documentation bug fix & lua_safe_omni_modules option
Merge pull request #30: Update to Lua 5.2 keywords and standard libraries