lots of stuff for the building process
randomized build crashes introduced
builder: added string representations
bulider: prettified string representations
builder: partially fixed job abortion
builder: simplified abortion process
builder: own build job manager started
builder: own job manager structure implemented
builder: implemented parts of run() in BuildTarget
Merge branch 'next' into builder
Merge remote-tracking branch 'origin/next' into builder
builder: reworked code structure towards a worker thread based model
builder: cleanup variable names and __repr__
builder: further work on the automatic dependency management
builder: complete job depedency hierarchy implemented
builder: fixed a bunch of bugs
builder: another bunch of bugs hunted down
builder: fixed add_dependency procedure
builder: jobs now check needs_build, successfully simulating the build_process now
builder: simplified and fixed code, part 0