"python -m maidenhead" CLI, Python >= 3.7

• to_maiden() precision= is now positional argument
• Python >= 3.7 required
• to_location() now checks that string is even length
• CLI is now python -m maidenhead to avoid littering PATH with executable scripts as best practice

add center cell option

By default, maidenhead outputs location on southwest corner of grid. added cli --center and to_location(...,center=True) option for more intuitive grid center location. By @Sylogista

CI: added python 3.6 to help ensure we don't botch older python.

python >= 3.6, python -m maidenhead

Python >= 3.6 required

cleanup testing, make python -m maidenhead cli in addition to console_script

cleanup internals

• remove deprecated functions
• cleanup test and need for mock
• eliminate excessive print precision for lat/lon--10 meters is more than adequate

modernize packaging, improve CLI

thanks mostly to @apast for modernizing the Pytest and CLI

using src/ package layout

Increase test coverage, fix Google URL

• Google Maps URLs work again
• allow coordinate tuple or lat, lon input
• remove discontinued NonSense maps

modernize CI template and metadata

Allow Python >= 3.5

simplify API

lat and lon are input as two variables now.
updated Julia code.

Modernize setup and test

• pep8, mypy type checking
• setup.cfg
• readme rst => md