Creation of the Manhattan example

* Added simulators
* Added project
Fix Manhattan example

* Fixed colorscale colors format
* Reverted correct colorscale in kml observer test
* Added to examples tests
Removal of constraints on required variables at a previous time step

* Removed required PREVVAR from signature macros
* Updated consistency checking in Engine and ProjectChecker classes
* Updated information display for variables in OpenFLUID-Builder
* Removed deprecated pretestConsistency in Engine class
* Adapted tests

(closes #154)
Add Monitoring and Model tests