Replace the FLAVORS-based split (qt6/nogui) with SUBPACKAGES:
gui, mantrans, guimantrans.
- SUBPACKAGES=gui mantrans guimantrans
- SELF_DEPENDS.gui=main, SELF_DEPENDS.mantrans=main, SELF_DEPENDS.guimantrans=gui
- Remove FLAVORS and flavor-specific variables
- Consolidate USES/USE_GL/USE_QT to always use qt6
- Remove GUI and MANTRANS OPTIONS (now subpackages)
- Move MANTRANS BUILD_DEPENDS (po4a) to common BUILD_DEPENDS
- Convert pkg-plist markers: %%GUI%% -> @@gui@@, %%MANTRANS%% -> @@mantrans@@, %%MANTRANS%%%%GUI%% -> @@guimantrans@@