Refactor and enhance logic, add more tests, docstrings, dev instructions

What's Changed

• Refactor logic
• Skip rotation when an angle is close to zero to avoid unnecessary operations and wrong "_rotated" values
• Handle polygon vertex duplicates and internal rings properly
• Update test cases to cover new edge cases
• Add more docstrings
• Add dev instructions

Full Changelog: 1.0...1.1

QGIS3

• QGIS3 support
• fixed bugs
• added tests

Processing

changelog 0.3
- migrated to Processing algorithms; full refactoring
- much faster
- possibility to write to the new layer all or only selected polygons
- possibility to rotate or not rotate multipolygons
- each polyline of the multipolyline is processed as a separate
- the new "_rotated" field is not duplicated if it already exists

i18n

Translation into Russian and Ukrainian

Polygons Parallel to Line

Changelog:
Plugins works much more faster by using spatial index and PyQGIS methods instead
my reinvented wheels.
Added progressbar.
Added possibility to rotate only selected polygons.
New icon.
Only english comments inside code.
Adding new field 'rotated' to polygonal layer. Rotated polygons takes value '1'.

Polygons Parallel to Line

0.1

Version 0.1