Merge pull request #84 from DLR-TS/feature/signals_implementation

Feature: add signal mesh creation

update README.md - add Viewer section, include road network mesh in e…

…xample

Merge pull request #51 from victorjarlow/fix_isnan_template

Bug fix where isnan <double> template specifier causes compilation errors

major refactor - simplify architecture and code, reduce ptr usage, le…

…ss memory management, introduce 'LaneKey'

* reduce memory management and dynamic allocations, make most objects local members
* reduce the usage of pointers to a minimum, only used in RefLine to store different RoadGeometries
* move functions from Lane and LaneSection to Road, more logical as Road has all information to generate meshes
* get rid of pointers to parent objects, not needed anymore as functions moved to Road class
* add information to make odr objects clearly assignable in road network (road id, lanesection s0, lane id..)
* viewer - remove bindings from Embind.cpp that would require adaption to new API (TODO), adapt viewer

Revert using 'GLM' lib