BNL license text approved by Dorene.

To be merged to each diffpy package repositories.
Use Columbia for source started at CU.

Fix year for an earlier source files.
Fix Columbia Trustees name and copyright year range.
Fix header texts to uniform format.

Also, use a common product name libdiffpy.
Rename LICENSE.txt to LICENSE_DANSE.txt.
Fix BSA BNL name in file headers.
Add BNL license text.

Merge branch 'license' from diffpy-release.
Add link to contributors page on GitHub.
Add example for test compilation with the library.
Fix BSA header in the features.hpp template file.
Change copyright holder in version.hpp to BSA.

Even if started earlier, version file should have the latest copyright
holder.
Remove all rights notice, but keep contact information.

Copyright on BV parameters is held by I. David Brown.
We still want to state what changes were made.
Avoid using ICSD cif files in unit tests.
Support alpha and beta pre-release markers.

For alpha or beta releases DIFFPY_VERSION is decreased by 500.
This ensures version number will be higher in actual release.
Ensure features.hpp is built with the lib alias.
update the doc to 1.2a0
link instalation in doc to README.rst on github
Use full install_name for libdiffpy build on Mac OS X.

This supports linking and use of build/.../libdiffpy.dylib
from any path.
Preserve settings when replacing PQEvaluator.

PairQuantity::setEvaluatorType now preserves settings such
as useFullSum or parallel-run variables from the replaced original.
Sort distance entries by pointers.

No need to create a bunch of vectors.