When building from git it will add targets to generate the swig files.
When building from tarball it will just point at the generated source
files from the tarball.
I.e., remove the shell invocation and with it the need to set the shebang.
Surprisingly this required some build-system modifications particularly
for cmake in order to correctly set the environment.
It is split into
- /libgnucash (for the non-gui bits)
- /gnucash (for the gui)
- /common (misc source files used by both)
- /bindings (currently only holds python bindings)
This is the first step in restructuring the code. It will need much
more fine tuning later on.
