Skeleton project data

This provides skeletons needed for process/solver class and a reworked `ProjectData` class.
All files from `OGS/` dir are distributed in the new `ProcessLib/` and `Applications/` directories and the `OgsLib` is also substituted with `ApplicationsLib`.
The new structures are used in the [GroundwaterFlow](https://github.com/endJunction/ogs/tree/GroundwaterFlow) and [CommandLineApplication](
https://github.com/endJunction/ogs/tree/CommandLineApplication] branches.

**For easier review please note:**
 - Most commits are just removing files.
 - Changes on files with one to three changed lines are adjustments of the includes or namespaces.
 - The interesting stuff consists of the new/moved files listed below.

Please take a look on (buttom-up order):
 - ProcessLib/BoundaryCondition
 - ProcessLib/InitialCondition
 - ProcessLib/ProcessVariable
 - ProcessLib/Process
 - ProcessLib/GroundwaterFlow
 - Applications/ProjectData
I think to removed it If there is not any other class name has string of  "GroundwaterFlow" because it is derived from class Process.  Otherwise, keep it as it is.

On the other hand, if term of ''Process'' is included, one may wonder whether this class defines physical properties only if he glances at the class name first.  Of course, you can doc the class highlighting  its tasks such as ''The class specifies variables, mesh, BC/IS and other information for  numerical modeling of groundwater process  in porous media''