These changes to SConstruct allow a simple way to include external projects with custom include / library paths by extending the [libraries] and [includes] sections of the build.conf file:

[libraries]
expro = /home/user/share/expro/lib
[includes]
expro = /home/user/share/expro/include

Effects:

• -I/home/user/share/expro/include is added to all compiler calls
• -L/home/user/share/expro/lib is added to all linker calls
• -lexpro is added to all linker calls (determined by the expro key in the [libraries] section).

The inclusion of gtest, std and tbb works as before.

I'd propose including these in the main repository as they streamline the integration of external projects for all contributors (and all forks).

Backported from rolandglantz/networkit.