vim-patch:7.4.203

Problem:    Parsing 'errorformat' is not correct.
Solution:   Reset "multiignore" at the start of a multi-line message. (Lcd)

https://code.google.com/p/vim/source/detail?r=fb24b025c7cf07db79a559a3091db42e02c1af86
Use cmake to find a lua executable

A lua executable is now required for the build process since a lpeg-based script
is used for generating a dispatch function and metadata for the msgpack API
frontend. This removes the need for setting the LUA_BINARY environment variable.
Fixes #518.
Add checks for lpeg/cmsgpack lua packages

These checks will stop the build process with meaningful error messages if
any of those packages are not installed.
Add lpeg as explicit third-party dependency

It was being installed because of moonscript, but now it's listed as a
dependency explicitly.