Add a 'clean' command

[Delivers #62882672]
Allow overriding default softcover build

[Delivers #65336996]
Merge branch 'stable' into 65336996-softcover-build
Add a stub Check module

[#61781888]
Add passing test for missing LaTeX dependency

[#61781888]
Align output

[#61781888]
Checking for all dependencies

[#61781888]
Add in dependency messages

[#61781888]
Rip out redundant dependency messages

[#61781888]
Polish work simulation

[Delivers #61781888]
Convert GIF to PNG on the fly

[Delivers #65068506]
Make KindleGen the default

[Delivers #65583588]
Add a more friendly exit for missing includes

[Delivers #63658440]
Add a custom preamble file

[#62899518]
Add a custom preamble override

[Delivers #62899518]
Add definition to get French version to build

[#65607946]
Move preamble to config dir

[#65607946]
Add lang translations yml

[#65607946]
Customize listings

[#65817046]
Add aside box label

[Delivers #65817046]