Fundamental & text modes: Tab: indent to align, or else to next tab stop or if mod. key: insert tabsize spaces

[xparq]

This is just as the configurable default. Various modes would have different params. E.g. my MD-like mode would probably have 2 as indent-size. (Shouldn't be called tab-size!)

• Aligned indent should just copy whatever whitespace the ref. line has!
• That "or else" means: if already aligned, or no ref. line "near enough" (cfg!), then proceed deeper.
• Reverse logic should be straightforward (but not sure).