passing 0 to git_strol(32|64) let the implementation guess if it's
dealing with an octal number or a decimal one.

Let's make it safe and ensure that both 'HEAD@{010}' and 'HEAD@{10}'
point at the same commit.

revparse: fix parsing of date specifiers

Replace incorrect 'it' with 'if' in documentation

More git_revparse_single ENOTFOUND use cases

Small revparse colon syntax improvements

Once a file is registered, there is no way to deregister it, even
after the structure that contains it is no longer needed and has been
freed. This may be the source of #624.

Allow and use the deregister function to remove our file from the
global list.

indexer: don't use '/objects/pack/' unconditionally

Not everyone who indexes a packfile wants to put it in the standard
git repository location.

Repo reinit fix + enhanced test coverage

Topic/refs fromglob

indexer: start parsing input data immediately

Currently, the first call of git_indexer_stream_add adds the data to the
underlying pack file and opens it for later use, but doesn't start
parsing the already available data.
This means, git_indexer_stream_finalize only works if
git_indexer_stream_add was called at least twice. Kill this limitation
by parsing available data immediately.