Switch to Qt Resource-based icons for Kexi with breeze as cross-platform default
- works on Linux & Windows
- old oxygen icons removed, breeze is the only fully officially supported theme; extra themes (as .rcc files) may be developed in separate repositories
- no support for themes from individual files: this can be developed and supplied as non-default option but for now no other icon theme is complete for Kexi
- two levels of icon resources: Kexi's own kexi_breeze.rcc and generic breeze icons breeze.rcc
- breeze.rcc should be generated from breeze-icons.git
- Icons from kexi_breeze.rcc have priority over breeze.rcc
- updated icons names based on the list from https://community.kde.org/Calligra/Icons/3.0
- Kexi icon names are enclosed with KexiIcon macro (and similar ones), generic breeze icons are enclosed with kiIcon macro (and similar ones); this is useful to track missing icons using scripts from devtools/iconcheck/
- by the way, move special pixmaps such as tableview_pen to resources