* Update ManualTests.md
Added manual test cases for Graphing mode in Calculator.
* Update ManualTests.md
Added line breaks to make my additions more legible, and added two more cases for testing the "too complex" and "unsupported" error messages for Key Graph Features.
Updating Contributing documentation:
* Adding reference to spec repository for feature development
* Adding localization issue template
* Adding clarifications for contributions and PRs
Saved 301 KB out of 9.2 MB. 15.8% per file on average (up to 82.2%)
Fixes #.
Saves 301 KB (although not all files are included in the build)
Description of the changes:
For PNG files: used a combination of Pngcrush, OxiPNG, AdvPNG, PNGOUT and Zopfli
For GIF files: used Gifsicle
How changes were validated:
No changes to behaviour or source code.
Previewed the changed files to make sure they still work
