Added class for function parameters with name, var repr and str
Created input and output parameter subclasses.
Added a description to Scilab function parameters.
Beefed up function.SciParam.__str__
Added Scilab data type (crudely)
Added type to string representation.
Extended __repr__ crudely, need to figure out how to deal with this.
Added size to parameters.
Merge branch 'feature/basic/scilab_function_parameter_encapsulation' into dev

Basic parameter encapsulation:

 - name (human readable)
 - var (name)
 - description
 - scitype (Scilab data type)
 - size (Scilab size)
Merge branch 'dev' into feature/basic/scilab_function_encapsulation
Created a class for housing sets of function parameters.
Refactored tests into fixtures (single- and multi-parameter)
Added a "stat" method to SciParamSet, returns member parameters/classes.
Added basic keymapping to SciParamSet
Refactored parameter test suite into fixtures.
Added a test for partially defined parameter str output (failing elsewhere)
Fixed the failed __str__ method for partially defined parameters.
Added a __str__ method to SciParamSet (doc comment style)
Added corresponding tests for previous commit.
ParamSet string representation now passes tests.