Eomaps

fixes
- there were some issues when specifying `"radius_crs"` in conjunction with `"cpos"` that are fixed now
- `"radius_crs"` can be one of `"in"`, `"out"` or any crs-specification recognized by `pyproj`
- `"cpos"` can be one of `"c"`, `"ul"`, `"ur"`, `"ll"`, `"lr"`
- fix typo in README: `xcoord="lon"` and `ycoord="lat"`
- use explicit "VERSION" file to specify module-version in one place

new
- `trimesh_rectangles` has been added as a possible plot-shape (e.g. `m.set_plot_specs(shape="trimesh_rectangles")`
(it uses a triangular mesh for plotting which is useful for contour-plots since pixel-boundaries are invisible)
- option to copy the data with `m.copy(copy_data=True)` has been added

fixes
- copy now performs a deep-copy of all properties
- make `geopandas` an optional import (basic functions do not require geopandas)
- add `pyepsg` as dependency
- use `xcoord` and `ycoord` as labels for annotations
- cleanup callbacks if figure is closed

new
- `add_marker()` function added to manually add markers
- `add_annotations()` function added to manually add annotations
- annotate can now be used on multiple buttons
- add `text` argument to `m.cb.annotate` to manually specify the text
- add `m.cb.clear_annotations()` function to delete annotations
- add `savefig` function to save the image
fixes
- fix permanent annotations
- + more fixes + more unittests

new
- allow multiple callbacks of the same function (using different mouse-button assignments)
- add option to make annotations permanent `m.cb.annotate(... , permanent=True)`
- add option to format annotation display via `m.cb.annotate(..., val_fmt=<callable>)`
- add `m.cb.mark` callback (e.g. to overlay markers around selected points)
- all callback-returns are now accessible via `m.cb...`
- add `m.cb.cb_list` (e.g. a hardcoded list of available callback functions)
fixes
- better fetching of background for blitting (now also works with multiple callbacks)

This is a first (beta) release... use with care!