fix cross references

branches: 1.8.2; 1.8.30; 1.8.34;
Use .In instead of .Aq Pa for header files.

Convert TNF licenses to new 2 clause variant

branches: 1.6.32; 1.6.34;
Pa Aq -> Aq Pa.

DMA, not dma nor Dma.

Edit -mdoc usage.

* There is no -indent option to .Bd or .Bl, although you would
never know that from its frequent use in this tree. There is a
"-offset indent" combination that makes sense, and you can certainly
say "-width indent".

* Also, you can't markup the -width option argument, tho you CAN
use a callable macro. So "-width Ar filename" doesn't make sense,
but either "-width Ar" or "-width filename" does, as might something
like "-width xxfilename" for a little extra space.

* There are a lot of needlessly complex hanging tag macros in man4 used
to create simple item lists. Those should be simplified one of these
days before someone copies and edits yet another man4 page.

Sort sections.

More and more of .Os cleanups. .Os is defined in the tmac.doc-common file,
so we shouldn't override it with versions in the manpages. Many more to
come.

Add a manual page for the Amiga custom chip floppy disk controller device,
mostly geared towards explaining the pseudo-partition encodings; with input
from Ignatios Souvatzis.