Fix PATH not being set in global env

Also, always set CMAKE_PREFIX_PATH
Further separate downloading and extracting source
Implement basic enum functionality
Implement an 'interactive' install mode

It starts a shell after extracting the source to a package,
so that users have a chance to look at the source and test if it will
build
Fix typo
Use 7z on Windows exclusively
Add workspace_dir to the BuildContext
Add an option for ignoring non-zero exit status
Make FileSet paths absolute
Fix recreating a directory on Windows
Allow the user to add dirs to formula search path
Allow specifing a formula inside a kit using a dot

The syntax is: <kit name>.<formula name>
The platform specific directories inside the kit are searched as well
Add an option for force installing a formula

This way the user does not have to first run uninstall if the installation
was incorrect in someway. It is really only usefull when developing formulas
Improve uninstalling packages

Now packages that require the package being uninstalled are uninstalled
as well
Add a command for creating an archive of a bundle
Forgot to call uninstall on the package itself
Fix errors in LibBundle
Handle the case when the tar is inside a directory
Fix bug caused by having a list as default arg
Enable building x86 and x64 with both vc9 and vc12