HOW TO RUN SCRIPT TO GENERATE .h FILES FROM .svg FILES
---
svg_to_headers.sh, will convert the svg files in ./svg to the
specified size of .png which will then be converted to header files each
containing a bitmap, formatted into a c-style array for use by the AdafruitGFX
library. The output files will be in a new directory, ./icons. To add the new
icons, you must manually move the newly generated icons folder to
platformio/lib/esp32-weather-epd-assets/icons.

Usage:
  bash svg_to_headers.sh <size_of_output_image>

Dependencies:
  Inkscape - Inkscape's cli is used to convert .svg to .png
  Python3 - to run png_to_header.py (in this folder)

To regenerate all icons execute the following command:
  $ make

Don't run `make -j`, Inkscape has a known bug when running svg to png
conversions in parallel.
  https://gitlab.com/inkscape/inkscape/-/issues/4716

THE ICONS IN THE SUB-DIRECTORY ENTITLED 'svg' REMAIN LICENSED UNDER THEIR
ORIGINAL LICENSE AGREEMENTS. SEE CITATIONS BELOW FOR MORE DETAILS.

Citations:

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.svg files prefixed with 'wi-' ('wi-**.svg') in the sub-directory 'svg'
  Retrieved from: https://github.com/erikflowers/weather-icons
  Weather Icons licensed under SIL OFL 1.1: http://scripts.sil.org/OFL
  Code licensed under MIT License: http://opensource.org/licenses/mit-license.html
  Documentation licensed under CC BY 3.0: http://creativecommons.org/licenses/by/3.0
********************************************************************************

********************************************************************************
.svg files prefixed with 'battery' (battery**.svg) in the sub-directory 'svg'
Visibility Icon 'visibility_icon.svg' in the sub-directory 'svg'
  Retrieved from: https://fonts.google.com/icons
  Licensed under Apache License, Version 2.0: https://www.apache.org/licenses/LICENSE-2.0.txt
********************************************************************************

********************************************************************************
House Icon 'house.svg' in the sub-directory 'svg'
  Retrieved from: https://seekicon.com/free-icon/house_16
  Licensed under MIT License: http://opensource.org/licenses/mit-license.html
********************************************************************************

********************************************************************************
.svg files prefixed with 'wifi' (wifi**.svg) in the sub-directory 'svg'
Warning Alert Icon 'warning_icon.svg' in the sub-directory 'svg'
Warning Alert Icon 'error_icon.svg' in the sub-directory 'svg'
  Retrieved from: https://github.com/phosphor-icons/homepage
  Licensed under MIT License: http://opensource.org/licenses/mit-license.html
********************************************************************************

********************************************************************************
House Icon 'house.svg' in the sub-directory 'svg'
  Retrieved from: https://seekicon.com/free-icon/house_16
  Licensed under MIT License: http://opensource.org/licenses/mit-license.html

'house_temperature.svg', 'house_humidity.svg', and 'house_rainsdrops.svg' were
created by transforming icons from https://github.com/erikflowers/weather-icons
with 'house.svg' and as such are
  Licensed under SIL OFL 1.1: http://scripts.sil.org/OFL
********************************************************************************

********************************************************************************
'ionizing_radiation_symbol.svg' in the sub-directory 'svg'
  Retrieved from: https://svgsilh.com/image/309911.html
  Licensed under CC0 1.0: https://creativecommons.org/publicdomain/zero/1.0/
********************************************************************************

********************************************************************************
'biological_hazard_symbol.svg' in the sub-directory 'svg'
  Retrieved from: https://svgsilh.com/image/37775.html
  Licensed under CC0 1.0: https://creativecommons.org/publicdomain/zero/1.0/
********************************************************************************

********************************************************************************
Wind Direction Icons 'meteorological_wind_direction_**deg.svg' in the
sub-directory 'svg'
  Retrieved from: https://www.onlinewebfonts.com/icon/251550
  Licensed under CC BY 3.0: http://creativecommons.org/licenses/by/3.0
********************************************************************************
