Update PYTHONPATH
Update PYTHONPATH

 - Adapt to the move of tests.py to binding/python-examples.
 - Support "make check" from a separate build directory.

MadBomber/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,MadBomber/link-grammar,MadBomber/link-grammar,opencog/link-grammar,MadBomber/link-grammar,ampli/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,MadBomber/link-grammar,ampli/link-grammar,linas/link-grammar,linas/link-grammar,linas/link-grammar,opencog/link-grammar,MadBomber/link-grammar,opencog/link-grammar,opencog/link-grammar,MadBomber/link-grammar,opencog/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,ampli/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,ampli/link-grammar,MadBomber/link-grammar,ampli/link-grammar,linas/link-grammar