fix for possibly invalid core calculation
Introduce lazy sessions

Session contexts are only created when requests actually change data,
instead of creating contexts whenever a session starts.
Cleanup usage of boost optional
Merge pull request #277 from bastih/feature/lazy_sessions

lazy sessions
Silence warning in dictionary tests
Remove unused stdlib.hpp
Enable building in subfolders
Merge pull request #288 from bastih/master

Enable building in subfolders
Addin Profiling Path option to Settings and SettingsOp
Merge pull request #251 from lordgeorg/core-fix

fix for possibly invalid core calculation
fix for possibly invalid core calculation
Merge pull request #289 from hyrise/feature/profiler_helper

Addin Profiling Path option to Settings and SettingsOp
Merge branch 'master' into feature/SubString
append substring to input table