Store more information in the symbol table

Types of instance parameters of parameterised interfaces are stored in the
symbol table, i.e. InterfaceRefDeclaration objects carry them.
Add analysis of task posting expressions

Expressions that cause a task to be posted are now analyzed and detected errors
are reported.
Implement a facade hierarchy for interface references

A small hierarchy of facade classes for interface references is created. It is
intended to provide an easy access to the information about the reference and
the interface itself, e.g. about commands and events declared in the interface.
The substitution of types if the interface is generic is handled transparently
by a facade. The facade for an interface reference is available after calling
method:

pl.edu.mimuw.nesc.declaration.object.InterfaceRefDeclaration.getFacade()

after the whole specification of the component has been parsed and processed.
Add analysis of interface references

Interface references in components specifications are now analyzed and all
detected errors are reported. The count and correctness of provided generic
parameters are checked. It is checked if type limits that are introduced by
attributes in declarations of interfaces generic parameters are obeyed.
Add checking correctness of NesC calls

Events signaling and commands calls expressions are now checked during the
semantic analysis and detected errors are reported. Moreover, objects in the
symbol table that represent bare commands or events or implementations of
commands or events from interfaces contain instance parameters if they are
present in corresponding AST nodes.
Fix types substitution for generic interfaces

Types substitution now works for derived types, e.g. if a referenced type of
a pointer type is an unknown type.
Allow a void pointer to take part in addition operations

Addition operations that involve adding an integer to a pointer of type 'void*'
are now permitted. Their presence causes emission of warnings (instead of
errors).
Add tests for the analysis of NesC calls