Features/bug fixes

#### feature.py
`values` is a function in the `feature` module. Simply printing `values` just printed the `__str__` of the function.

#### property.py
Sorting by `Feature` instance rather than the feature's name produces unpredictable results since sorting instances of classes that don't have comparison methods implemented end up sorting by the instance's id() which, in CPython, is usually the instance's memory address.

This would cause system tests to fail randomly. For example, consider the configuration `<toolset>adi <toolset-adi:family>bf <toolset-adi:version>7.2`. The paths created for that particular toolset would alternate randomly between `adi-bf-7.2` and adi-7.2-bf`. So, checking for an `expected_addition()` in the system test would fail randomly.

#### build_system.py
`PARALLELISM` was converted to a string.

Support for `--version` was added.