Install python modules from build directory (issue 575960043 by address@hidden)

[hanwenn]

https://codereview.appspot.com/575960043/diff/557650043/make/lilypond-vars.make
File make/lilypond-vars.make (right):

https://codereview.appspot.com/575960043/diff/557650043/make/lilypond-vars.make#newcode20
make/lilypond-vars.make:20: export
PYTHONPATH:=$(top-build-dir)/python/$(outconfbase):$(PYTHONPATH)
This will potentially make the out-www build fail. It's much better to
load the source files directly, because they're always there and they're
always up to date.

https://codereview.appspot.com/575960043/diff/557650043/python/GNUmakefile
File python/GNUmakefile (right):

https://codereview.appspot.com/575960043/diff/557650043/python/GNUmakefile#newcode27
python/GNUmakefile:27: local-test: default
if you do it like this, this should depend on
$(outdir)/book_base_test.py and the rule should use $< . Otherwise,
editing the test file doesn't redo the copy.

https://codereview.appspot.com/575960043/