Added check_checksum for windows

Defined CHECKSUM_TOOL_PATH for checksum tools Mac/Win
Added check_checksum for windows
Added setlocal enableextensions enabledelayedexpansion to instructions
prefix on windows
EXIT_ON_ERROR label will exit 1 if no exit code was set
Minor typos fixed

Reviewed by Shai
Merge branch 'master' of https://github.com/wavesaudio/instl

Conflicts:
	ChangeLog.txt