closes: #1374 .
Use SPDX short-form identifiers instead of lengthy copyright
header to document per-file license and copyright.
This commit updates all files under src/ directory where applicable
as well as org.flameshot.Flameshot.metainfo.xml.
closes#11
Add an initial version of the text tool.
This commit adds:
- Basic text tool.
- On demand thickness and color update.
- Generalized logic for future widget based tools.
