* Polish translation improvements

Mostly grammar updates, making it more clear and look more official, by using less colloquial words.
In some places I made it more understandable and true to original.
The most striking thing in previous translations is "Free" translated as "Free to download" not as "Free space" meaning.
I'm not sure if I should change the last translator on top, but I updated the revision date and filled the translators as they are now on the bottom.

* Polish Translation - Fix clipped message

* Polish translation - Remove broken newline

* Add a shellscript to convert tsv to database file

Updated the build environment to use Ubuntu 22.04 and installed Python 2.7.

* Add build docker image

* use separated makefile for docker builds

Co-authored-by: Damián Parrino <[email protected]>

* use proxy

* Update size formatting to use localized units

* Replace string literals with constants

* Update size unit definitions to uppercase

* Bump version from 1.2.4 to 1.3.0

* Refactor HTTP content size function and cleanup

* Refactor download size handling in pkgi_download.c

* Change license from MIT to GPL

* icon extern def

* Replace icon file saving with predefined PNG

Added new version v1.3.0 details to CHANGELOG.