Lua-Support: Added documentation. Minor changes.

- Added 'g:Lua_BinPath' to set the path for all executables at once.
- Minor corrections.
- Added a documentation.
- Added a readme.
- Added suggestions for the customization of .vimrc and .gvimrc.
- Added a new codesnippet.
- Minor changes to the templates.
Matlab-Support: Minor corrections and additions.