Metpy

Issues closed

**Issues**
- Issue 246 - Add conda to install guide
- Issue 245 - TextCollection broken with PathEffects and empty strings
- Issue 244 - Possible bad dates in Level3File
- Issue 233 - Problem with GINI Polar Stereographic image
- Issue 232 - Bad parcel profile
- Issue 220 - Possible error in gridding_functions.py

In this release 6 issues were closed

**Pull requests**
- PR 248 - Small fixes
- PR 237 - Fix parcel_profile
- PR 222 - BUG: Fix buffer argument (Fixes 220)

In this release 3 pull requests were merged

- New calculations:
- Saturation mixing ratio (163)
- Equivalent potential temperature (163)
- Coriolis parameter (205)
- Level of free convection (LFC, 201)
- Added provisional support for objective analysis/regridding (186):
- Barnes
- Cressman
- Nearest neighbor
- Natural Neighbor
- Radial Basis Function interpolation
- Added support for downloading upper air data from Wyoming and Iowa State archives (202)
- Bug Fixes:
- Fixed value of omega in `constants` (173)
- Updated value of Earth's radius to match GEMPAK (173)
- Fixed 180 degree offset in wind direction calculation (179)
- Fixed potential temperature with non-millibar pressure units (165)
- Unique authors:
- kpozsonyi
- ahaberlie
- deeplycloudy
- jrleeman
- dopplershift

- Fixes:
- Make compatible with pint 0.7
- 138 - Fix for polar stereographic projection in GINI files
- 139 - Fix for Mercator projection in GINI files
- 148 - Fix reading some TDWR NIDS products
- Other notes:
- Use conda-forge channel now for conda packages
- Now tested on AppVeyor for Windows
- Improved example list in docs--now has a gallery of images from the notebooks

- Features:
- Station Plots (125): MetPy can now be used to create station plots, making use of a special weather symbols font for present weather, sky cover, cloud types, etc. The documentation has examples showing how to use this support.
- GINI file support (114): MetPy can read the NWS' GINI files, which are used to transmit satellite images over NOAAPORT.
- Hodograph (111): MetPy can be used to make hodographs (plots of wind components with height).
- Skew-T improvements (111): Skew-T plots are now usable with matplotlib's subplots and GridSpec.
- Added `resample_nn_1d` for reducing an array of data to the points closest to a set of levels. Contributed by ahaberlie .
- Fixes:
- 84 - Fix relative humidity units for heat index (added our own unit to designate a percentage)
- 81 - Fix `get_with_steps` for getting colortables
- Other notes:
- Moved from nose to py.test for testing
- Added image comparison-based tests for testing plot methods
- Improved arrangement of documentation--removed some extra layers of nesting.

- Added `viridis` colormap 75
- Added NEXRAD level 2 example 45
- Split `get_speed_dir` into `get_wind_speed` and `get_wind_dir` 66
- Fixed clipping of wind barbs on skewT 54
- Fixed broken NIDS attributes on Python 3 55
- Fixed bug with units on `heat_index` 56
- Moved to use `logging` rather than `warning` for issues beyond user control 51
- Clarified units in `get_wind_components` 46
- Other minor documentation fixes