remove some code lint
remove duplicate edges from NodeBasedGraph
fix short variable names and long lines
Fixes build using gcc 4.9 with LTO.

Otherwise sem_close is not found.
add more comments and rename a couple of badly named variables
Merge pull request #1051 from TheMarex/linker-fix

Fix linking for linux
make sure result is always > 0, hits when origin and destination are on the same one-way segment in reversed order
include <string> as it is needed
simplify static asserts

Simplify static asserts to make them compatible with older compilers and MSVC 2013
Merge pull request #1063 from alex85k/patch-6

simplify static asserts