Add cabal binaries to PATH

[mcandre]

Could future installers add C:\Users\SOME_USER\AppData\Roaming\cabal\bin to PATH ?

Sure, we can add it manually, but newbies shouldn't have to figure out why this happens:

C:\>cabal install bloxorz
...
C:\>bloxorz
'bloxorz' is not recognized as an internal or external command,
operable program or batch file.

[refold]

Ah, that's because cabal now installs everything to the user's home directory by default. Sure, this can be done.

[refold]

This was fixed in some previous release. We add "$APPDATA\cabal\bin" to HKCU/PATH.