Cmappy

- Added math sub-package with methods to z-score & calculate (fast) correlation and covariance values on matrices, as well as methods to use these operations on gct/x/oo objects
- Clarity improvement to error messages
- Speed improvement to id parsing

- Renamed concat_gctoo.py to concat.py, slice_gct.py to subset.py, and slice_gctoo.py to subset_gctoo.py for consistent file naming

- Added tests for gctx2gct and gctx2gct

- Removed use of mocking in testing by having main() quickly call another main method (e.g. slice_main or concat_main)

- Added methods for fast correlation and/or covariance calculations (fast_cor, fast_cov)

- Tutorial updates

- Import statements updated to absolute imports using CMap style guide
- Bug fix for DataFrame checks in GCToo class constructor
- Additional bug fixes

v.3.0.0
* Removed Python 3.4, 3.5, 3.6 support. Apologies to users; found that migrating to Python 3 introduced more issues than expected and so will be removed until development progresses further.
* GCTX files only: added chunking (for data matrix only) and gzip compression (for metadata only). Defaults for this behavior are set for compatibility with cmapM and cmapR packages.
* Issues with travis fixed
* Bug fixes
* Documentation updates

* Added support for Python 3.4, 3.5, 3.6

* Added compatibility with pandas 0.20
* Added test coverage for command line methods
* Added option to return just metadata to GCT

* Added set_io subpackage
* Added command line tools to pandasGEXpress
* Bug fixes