Cleaned up some author method documentation
Updated supported version of libgit2
Added dependency on pygments-cl-repl
Merged asdf system files into one

This uses the new / separator to designate child packages.
Cleaned up some API doc strings
Move change log off index page
Updated index page
Fixed up many documentation strings

This change also make the pages more consistent.
Added better index page and removed texinfo doc
Released 0.20.0
Added simple tests for version and capabilities functions.
Updates to get all tests running for version 0.21.0

+ Moved libgit2-types to libgit2-types-grovel and created a new
libgit2-types meant for frequently used types that are not grovelled.

+ Defined git-buf type used to get patches.

+ git_index_add requires the filemode to be set.

+ When creating new references, a signature and log message are now
used.

+ In test diff-working, file-b appears to no longer have a valid UID,
test has been corrected.
Renamed LIBGIT2-CAPABILITIES to LIBGIT2-FEATURES.

Added :ssh feature.
First take at cloning.

Added CLONE-REPOSITORY method as well as the callbacks and classes necessary for authentication.