Merge pull request #11 from jingpengw/master

release the package to pypi

Reset version tag to v0.8

Reset version tag to v0.7

Bump version

Bump version to 0.5

Block on concurrent compile of same module

This fixes the remaining race condition if several processes try to
compile the same module (with the same merge function) at the same time.

Compile C++ code (lazily) at runtime

This allows passing the edge scoring function as a C++ type string at
runtime. The code will only be compiled, if a previous version does not
exist yet.

Bump version to 0.2