Pyrsl

* add command line argument for quieting insert mismatches encountered while loading models
* check that parameter count == argument count in function invocations

* Update to pyxtuml version 2, which means:
- Swap order of phrases in navigations
- Make referential attributes read-only
- Support unrelate operation on associations formalized using identifiers (e.g. super/sub type associations)
- Support navigations across associations classes without explicitly stating the association class name in the expression
* Use short circuit evaluation of expressions containing 'or' and 'and' operators
* Allow unique_id type parameters
* Allow specification of key letters within angle brackets for applicable parameter types. [Example](http://pyrsl.readthedocs.io/en/master/language-reference.html#defining-functions)
* Add support for "relate/unrelate using" syntax, inspired by OAL syntax. [Example](http://pyrsl.readthedocs.io/en/master/language-reference.html#connecting-instances)
* Add support for modulus operator (%)
* Add support for the caret operator (^)
* Cast left-hand operand to a set if the right-hand operand is a set
* When a fragment is printed, display its key/values
* Improve type checking of instance and instance set parameters
* Drop comments during tokenization

* bumped requirements for pyxtuml to the interval [1.0, 2.0[
* bumped development status to Production/Stable
* removed python3 from list of supported language flavors
* removed obsolete bundle script. Use python setup.py bundle instead
* added a simple linter, python -m rsl.lint

- update for api changes in pyxtuml v0.9
- allow unit testing of individual test cases

- extends $info with arch_file_path and arch_folder_path, and makes arch_file_name represent the basename of a file path
- allows parameters that have the same name as keywords, e.g. from
- improves handling of invalid control statements, .e.g files containing only a single dot (.)
- improves first/last operator when used in nested set iterations
- adds a new (cross-platform) bundle command that bundles pyrsl into a pyz file (gen_erate.pyz)

rsl: added additional language features inspired by OAL (relate/unrelate/delete)
win32: use python2.7 when producing .exe binaries
win32: improved support for accessing the current user id, i.e. "${info.user_id}"