jobs: fixed segmentation fault when thumbnail loader abort

JobManager grab a copy of the CWorkItem then release the lock,
if the cancel occurs right then. The callback can be in progress
after the CancelJob finishes.

Several locations assume it's safe to delete the callback target
after having cancelled pending jobs, so make sure we wait for
any in progress job completions or job progress calls.
[win32] Update python package to 2.7.8
Merge pull request #5764 from elupus/jobsegv

jobs: fixed segmentation fault when thumbnail loader abort
Merge pull request #5765 from Karlson2k/win32_python278

[win32] Update python package to 2.7.8
fixed: use the proper make instead of calling 'make' directly

fixes builds on freebsd
cmake buildsystem
add tests needed by new u16 string stuff
wrap cmyth properly
move some more install related stuff to install script
move all install code to platform install script
allow building without doxygen
fix building with yajl2
generate scripts in a subdir to avoid problems configuring in top dir
properly wrap library.xbmc.foo
link to threading lib
remove duplicate mpeg2 entry
properly locate java and swig

also use the detected paths for java, swig and doxygen
cosmetics: move all depends together for better readability
changed: build with a prefix to avoid cluttering the build dir

some peeps still do in-source builds out of old habits. this is
to annoy them slightly less, though they should STOP doing in-source
builds in the first place
grm