Add Code Compare v2.80.4 as a merge / diff tool for Windows

Code Compare is a commercial file comparison tool for Windows, see

    http://www.devart.com/codecompare/

Version 2.80.4 added support for command line arguments preceded by a
dash instead of a slash. This is required for Git for Windows because
slashes in command line arguments get mangled with according to these
rules:

    http://www.mingw.org/wiki/Posix_path_conversion

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -1319,7 +1319,7 @@ _git_diff ()
 }
 
 __git_mergetools_common="diffuse ecmerge emerge kdiff3 meld opendiff
-			tkdiff vimdiff gvimdiff xxdiff araxis p4merge bc3
+			tkdiff vimdiff gvimdiff xxdiff araxis p4merge bc3 codecompare
 "
 
 _git_difftool ()

git-mergetool--lib.sh

@@ -126,7 +126,7 @@ guess_merge_tool () {
 		else
 			tools="opendiff kdiff3 tkdiff xxdiff meld $tools"
 		fi
-		tools="$tools gvimdiff diffuse ecmerge p4merge araxis bc3"
+		tools="$tools gvimdiff diffuse ecmerge p4merge araxis bc3 codecompare"
 	fi
 	case "${VISUAL:-$EDITOR}" in
 	*vim*)

mergetools/codecompare

@@ -0,0 +1,25 @@
+diff_cmd () {
+	"$merge_tool_path" "$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	if $base_present
+	then
+		"$merge_tool_path" -MF="$LOCAL" -TF="$REMOTE" -BF="$BASE" \
+			-RF="$MERGED"
+	else
+		"$merge_tool_path" -MF="$LOCAL" -TF="$REMOTE" \
+			-RF="$MERGED"
+	fi
+	check_unchanged
+}
+
+translate_merge_tool_path() {
+	if merge_mode
+	then
+		echo CodeMerge
+	else
+		echo CodeCompare
+	fi
+}