* Makes gdal an optional dependency

* Refactors all bae I/O into a single namespace.

* typos

* Fixes the gdal dependency test

* Adds tests for the JSON

* Tests fail without test data

* Updates for comments from @thareUSGS

* Adds ISIS3 V2 ControlNetwork Reader

* Adds hcube mixin object

* Added Socet Set GPF/IPF examples

* Added .prj and .sup examples that correspond to .ipf and .gpf Athabasca examples

* Add .atf example

* Removed erroneously-added .gpf files from SocetSet examples

good additions.

* Makes gdal an optional dependency

* Refactors all bae I/O into a single namespace.

* typos

* Fixes the gdal dependency test

* Adds tests for the JSON

* Tests fail without test data

* Updates for comments from @thareUSGS

* Adds ISIS3 V2 ControlNetwork Reader

These Eigen values only get written into the gpf only after the user saves the triangulation after running a solve.

Socet GXP gpf and ipf examples

Several lines have been added to GXP gpf file.

* Typo fixes in io_gpf.py. Column labels now match case of headers in Socet Set spec for GPF files.

* More typo fixes for GPF column labels in IO script and test data

* Adds prototype socet gpf read from @thareUSGS

* Adds test to gpf reader

* Adds length assertion and logic for dynamic cols

* removed static struct arr

* Finishing the merge cleanly

* removed assertTrue

* Fixes test to compare in/out files.

save_gpf seems to be working well. Note sure the test is ready though. It is there but uncertain if filecmp.cmp with shallow=True will allow it to pass since they are not exactly the same (e.g. number of decimal places). Also cat file be written too?

* Appveyor build for win32

* Type merging appveyor

* Adds prototype socet gpf read from @thareUSGS

* Adds test to gpf reader

* Adds length assertion and logic for dynamic cols

* removed static struct arr