Only build specific executables

[lostman]

Suppose I have a package foo which defines executables exe1, exe2 and exe3.

With cabal build I can compile a single executable:

cd foo/
cabal build exe1

This is incredibly useful for development. Otherwise, even for small incremental changes, all executables are rebuilt and the bulk of time is spent on that.

[snoyberg]

Please see #201, which I just implemented. It should now work to run stack build foo:exe1. If not, let's discuss on #201.

[RasmusWL]

For reference I will point to #1406 (stack 0.1.8 lost ability to build individual executables or library) so other people will realise faster that they are not idiots, and that this feature is just not working right now.