[WIP] IC/BC/ST tools for FEM

DO NOT MERGE THIS PR YET! 

This PR follows #369 and is aimed at providing the following features required for applying IC,BC1/2/3 and source/sink terms in FEM simulations
- Construction of distributed nodal values from a given spatial function
- Generating boundary mesh elements located on a given geometry (used for BC)
- ?: Integration over specified part of mesh (e.g. boundary integration, integration over parts of a domain)
- some more?

@rinkk In the past we had only the method ```getMeshNodeIDForPoint()```. Nori introduced this new method to class ```MeshNodeSearcher``` that will work for all objects of type ```GeoObject``` (for example ```Point```, ```Polyline``` and so on). Another possibility to implement this would be overloading of ```getMeshNodeIDs()```.