remove /ZM1000 from msvc builds

Updates config upon moving and deletion of branches

Pedantic ordering of GIT_UNUSED vs. variable declarations.

Progress callbacks

reset changes for merge

git_indexer_stats and friends -> git_transfer_progress*

Also made git_transfer_progress members more sanely
named.

Use libcrypto's SHA-1 implementation when linking to it

libcryto's SHA-1 implementation is measurably better than the one that
ships with the library. If we link to it for HTTPS support already,
use that implementation instead.

Testing on a ~600MB of the linux repository, this reduces indexing
time by 40% and removes the hashing from the top spot in the perf
output.

Add git_config_level support when handling config files

Added `struct git_config_entry`: a git_config_entry contains the key, the value, and the config file level from which a config element was found.
Added `git_config_open_level`: build a single-level focused config object from a multi-level one.

We are now storing `git_config_entry`s in the khash of the config_file

This can occur after a manual modification of a config file.

Save the autotag configuration for remotes

More orphaned head love