[CMake] NSIS template

[Andrea Crotti]

I'm working on the NSIS template and changing it to my needs, so 
unfortunately I also
have to really understand some more NSIS..

One thing that I found from the doc is that the LogicLib.nsh makes life 
a lot simpler.
All these strcmp would be simpler for example
   StrCmp $1 1 AddToPath_NT
     ; Not on NT
     StrCpy $1 $WINDIR 2
     FileOpen $1 "$1\autoexec.bat" a
     FileSeek $1 -1 END
     FileReadByte $1 $2


Are you in general interested in cleaning up / refactoring the NSIS 
template file anyway keeping
the same features?