Ensure build takes place within our build dir
Ensure build takes place within our build dir

Formerly, if I did:

  $ mkdir build && cd build
  $ cmake .. && make && make install

I would end up with a directory ../../build containing the tkp python module.
That doesn't make any sense -- it should be within the local build directory,
not somewhere else on the filesystem.

transientskp/tkp,bartscheers/tkp,mkuiack/tkp,bartscheers/tkp,mkuiack/tkp,transientskp/tkp