make installer find interpreter by short versioned name, eg. lua52.exe instead of lua5.2.exe
added platform detection 32/64bit
fix for 5.2 path variable
modified architecture detection as per http://support.microsoft.com/kb/556009
Merge pull request #163 from Tieske/interpreter_short_version

Windows; installer fix in finding interpreter, detecting 32/64bit and Lua 5.2 environment PATH variable