make it possible to merge vendor branches with 'got merge'

portable: add FreeBSD support This adds the capability to compile got-portable on FreeBSD.

portable: initial Linux compilation This commit modifies the GoT main branch to be able to compile it under linux.

fix another instance of 'got send' sending branches the server already has

move duplicated dial_ssh() and dial_git() functions into a common file 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.

make realloc_ids() malloc-like and do not overallocate Let realloc_ids() take as argument the number of entries to allocate. Do not allocate an extra chunk. ok stsp

drop realloc_ids() initialization calls, one of which had a typo realloc_ids() is called again in the loops that assign to the ID arrays, before the first assignment. ok stsp

do not send a pack file when 'got send' is only deleting branches The git protocol spec says the client MUST NOT send a pack file if the only command used is 'delete'. Fixes 'got send -d' against Github's server which closed the session upon receiving the empty pack file we sent. This problem wasn't caught by regression tests since git-daemon does accept an empty pack file. Problem reported by jrick.

fix the output of 'got send -d' upon success Previous output was: Already up-to-date New output is: Server has deleted refs/heads/branch Check this behavour in the related regression test.

add 'got send' command for sending changes to remote repositories Known to work against git-daemon and github Git server implementations. Tests by abieber, naddy, jrick, and myself. Man page additions reviewed by Lucas.