EHN: Add more to `info

EHN: Add `SAR` extraction.

FIX: Remove unnecessary `== True`

EHN: Improve source documentation

EHN: Add `valid_index()` and `flip()`->`flip_slice()`

EHN: I

FIX: Improved documentation in imports

FIX: Bug in `msg()` failinf for blank text

FIX: Remove list comprehension from `all()` and `any()`

FIX: Avoid using `fmt` not as `fmt()`

EHN: Implement `fmt()` and `fmtm()`, and fixes thereby

FIX: Updates in `pytk`

FIX: Minors

ENH: Import all symbols from `.raster_geometry`

FIX: Improved Gitignore