ok stsp

These functions are used by 'got send' and 'got fetch' in order to open network connections to a server. Move them into new file lib/dial.c and declare relevant functions in got_dial.h and lib/got_lib_dial.h. No functional change.

Known to work against git-daemon and github Git server implementations. Tests by abieber, naddy, jrick, and myself. Man page additions reviewed by Lucas.

This new diff implementation was started by Neels Hofmeyr during the u2k20 hackathon and now replaces diffreg.c code lifted from the OpenBSD base system. The integration of this code into Got was done by me. Got now uses the patience diff algorithm by default. The diff.git repository will remain the primary repository for the diff code, which already compiles and runs on other operating systems such as Linux. Any fixes and improvements for files inherited from the diff.git repository should be written against that repository and synced to got.git afterwards.

Always diff against latest version of file. This is much easier since there is no need to keep track of lines shifting around.