add common Makefile for Windows (32/64)
suppress warnings: include io.h and define lseek as shortcut to _lseek
suppress warnings: assign default value to some HANDLEs
suppress warnings: do not "use do{}while(0)" for Win64
remove redundant source: vimstack.c is included from proc_w32.c
suppress warnings: add explicit cast
suppress warnings: disable "unused argument (C4100)"
suppress warnings: add explicit casts
Merge pull request #37 from koron/improve_msvc_support

Improve msvc support
- Improved for Visual Studio support(KoRoN).
- Improved documentation.
- Improved documentation.
- Improved mac checker.
- Improved Mac checker.
- Improved vimproc#kill() behavior.
- Improved a bit.
add g:vimproc#SIG* constant variables
Merge pull request #38 from tyru/constants-for-signals

add g:vimproc#SIG* constant variables
- Fixed parse of backquote.
Merge branch 'master' of github.com:Shougo/vimproc