Inline fortran functions

This is a set Fortran 2003 modules that allows to call "formula" objects that resemble the Matlab inline functions (also called "anonymous" or "lambda" functions in other languages). User can give a formula in a string and evaluate it through an eval procedure. The implementations take advantage of the Fortran 2003 procedure pointers to speed up the formula evaluation.

These modules also permit to define "expressions". A expression is an uniform way to work with several data types: constants, interpolation tables, formulas and precompiled functions.

Finally, it is possible to work with "referenced expressions", that is, arrays of expressions associated to reference numbers.