treewide: correct several "up-to-date" to "up to date"

Follow the Oxford style, which says to use "up-to-date" before the noun,
but "up to date" after it. Don't change plumbing (specifically
send-pack.c, but transport.c (git push) also has the same string).

This was produced by grepping for "up-to-date" and "up to date". It
turned out we only had to edit in one direction, removing the hyphens.

Fix a typo in Documentation/git-diff-index.txt while we're there.

Reported-by: Jeffrey Manian <jeffrey.manian@gmail.com>
Reported-by: STEVEN WHITE <stevencharleswhitevoices@gmail.com>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/technical/pack-protocol.txt

@@ -199,7 +199,7 @@ After reference and capabilities discovery, the client can decide to
 terminate the connection by sending a flush-pkt, telling the server it can
 now gracefully terminate, and disconnect, when it does not need any pack
 data. This can happen with the ls-remote command, and also can happen when
-the client already is up-to-date.
+the client already is up to date.
 
 Otherwise, it enters the negotiation phase, where the client and
 server determine what the minimal packfile necessary for transport is,

Documentation/technical/trivial-merge.txt

@@ -32,7 +32,7 @@ or the result.
 If multiple cases apply, the one used is listed first.
 
 A result which changes the index is an error if the index is not empty
-and not up-to-date.
+and not up to date.
 
 Entries marked '+' have stat information. Spaces marked '*' don't
 affect the result.
@@ -65,7 +65,7 @@ empty, no entry is left for that stage). Otherwise, the given entry is
 left in stage 0, and there are no other entries.
 
 A result of "no merge" is an error if the index is not empty and not
-up-to-date.
+up to date.
 
 *empty* means that the tree must not have a directory-file conflict
  with the entry.