* Fixes 126 and PVL grammar issue

* Adds changelog.md

* Updates meta.yml for pvl version

* Adding Logos

* Update README.md

* Added GXP support to read_gpf()
Modified read_gpf() in io_bae.py to support reading of either legacy Socet Set-style GPF files or new Socet GXP-style GPF files. Function now takes a boolean, `gxp` to flag whether function should interpret input file as SSET or GXP style, defaulst to SSET style for backwards compatibility. Removed unused variables from read_gpf(). Field names are now hard-coded in the function, rather than generated dynamically. The hints about field names in the GXP-style GPFs are just complicated enough that hard-coding a list of field names into the function was the simplest solution. Datatypes for each field were already hard-coded, so hard-coding the names is stylistically consistent.

Partially address #24

* Deleted extraneous comment

* Added tests for read_gpf() and updated Socet GXP test data

* Updating test for read_gpf(), ticking minor version number

* Fixing fixtures...maybe

* Fixing fixtures...maybe

* Correct variable assignment in read_gpf(), more fixing fixtures

* Fixing test parameterization

* More test parameterization tweaks

* Adds dynamic reference indices to ISIS network writes

* Updates for comments

* Stub failing test

* Adds tests for referenceIndex in cnets

* Updates tests to check for warnings

* Removes travis

* Allows the user (or CI) to grab gdal from osgeo instead, if available

* Fixing the imported package

* The import error was causing travis-CI to fail.

* Reverting old PR edits and moving attempted oseo import to init

* Add .readthedocs.yaml file and correct tile for tutorials

* Also add documentation badge

* Move build documentation badge

Co-authored-by: Kristin Berry <kberry@gyro.wr.usgs.gov>

Updated for PVL 1.0

travis build fails because of no output for >10 minutes.  Removing quiet flag might generate additional output needed to keep the build alive.

Fix PVL import.

* Prepping for 1.2.4 release

* Update appveyor.yml

* Update appveyor.yml

* Supports covar when some are empty

* Adds tests for aprioriCovar

* Fixes 144

* Supports read/write, warn on pointLog

* Adds tests and fixes bugs that the tests identified

* Updates for comments

* updates tests

* shifting apriori line/sample during read in/write out

* making apriori values optional

Added check for repeated fields in protobuf

Added name un-mangling when writing ISIS controlentworks out

* Fixing to_isis / from_isis process

* Removed merge conflict

* Fixed tests

* First pass at shared field names

* Removed write changes

* Removed print

* Added better testing. Fixed weird choosername problem

* Adds computation of covariance matrix to utils

* Adds covariance matrix inside library

* Updates to_isis to use the 0.5 offset

* inverse correction on from_isis