Redmine: #2081

Redmine: #1937
in reflectometry examples

Redmine: #1860
1. Separate folder for reflectivity simulations added
2. New examples/tests for beam divergence in specular simulations
3. Corresponding amendments in PyPersistence/example_template.py

Redmine: #1860

Changed cross correlation length in tests to value that influences the scattering and fixed bug in export to python

All simulation examples now take argument -p or filename. All fitting examples are taken out from the persistence tests. All persistence tests pass, but they do not yet test persistence.

This resolves #1071.
Manually repaired AllFormFactorsAvailable.py.