Rewritten mesh and added a sfd3pt mesh
Work in progress on ghost points, awaiting tests
Added a new boundary condition: periodic

Dirichlet boundary condition supports a parameter 'a' as in 'u(0)=a'.
First working version of _one-dimensional_ ghost class.

What works:
- generation of ghost points using boundary conditions
- detection of temporal derivative
- while performing derivation commutation of derivatives is assumed
What was not tested:
- temporal derivatives
- different boundary condions on both edges
- only one mesh: sfd3pt was tested
What does not work:
- multiple meshes are not supported
- differentiation with respect to non-spatial variable
added a switch between lua5.1 and lua5.2
Added a working generic_function type.

This type extracts a function from an object file and provides an
interface to call such function.

No error handling yet.
Changed how the names of platonic types are read from lua file
Added code to cope with simple errors to generic_function_from_object_file
Icicles have been rewritten
First working version of ghost points, kind of slow
Implementation of ghost points was rewritten
Optimized join() function
Fixed a major bug connected to generating boundary values data
Removed some unused variables
Tweaked error reports a little
Icicles rewritten due to the bug involving automatic reallocation
At long last, the working version of icicles_wrap
Work in progress on generic icicles
Some changes to named_vector
Major refactoring