Removed cmake namespace stuff.

namespace won't work anyway because there would also be collisions
with header search paths, etc... so all we'll do is look for
import/export name collisions and warn about them
More dependency import/export stuff
Added 'open' verb to open project in IDE.

'gen', 'build', 'run', 'open' must be executed in a valid
project directory now.
Implemented module exports and imports