Update of CMake helper macro for building simulators

* Added building of simulators doc
* Added built simulators tests
* Added built simulators installation
Update of URLs of web links

* Updated main URL
* Updated other URLs
* Cleaned duplicate URL management in config files

(closes OpenFLUID/openfluid#139)
Update of software information

* Updated AUTHORS file
* Updated Copyright information dates
* Switched to version 2.0.0~alpha5
Redesign of macros for declarations in wares signatures 

* Removed redundant _SIGNATURE_ word in DECLARE_XXX macros
* Cleaned code
* Updated tests
Add of a primitive to get the scheduling constraint currently applied
Fix of scheduling macros for simulators signatures
Update of tests and doc

* Updated doc of ware methods
* Updated file format for input data tests
* Updated tests of input data primitives
Add of GNUplot observer for export simulation variables to graphs

* Added export.vars.plot.gnuplot
* Updated tests

(closes OpenFLUID/openfluid#56)
Switch to version 2.0.0~beta1