Mark strings for translation.

The procedure [mc ...] will translate the strings through msgcat.
Strings must be enclosed in quotes, not in braces, because otherwise
xgettext cannot extract them properly, although on the Tcl side both
delimiters would work fine.

[jes: I merged the later patches to that end.]

Signed-off-by: Christian Stimming <stimming@tuhh.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

lib/error.tcl

@@ -9,7 +9,7 @@ proc error_popup {msg} {
 	set cmd [list tk_messageBox \
 		-icon error \
 		-type ok \
-		-title "$title: error" \
+		-title [append "$title: " [mc "error"]] \
 		-message $msg]
 	if {[winfo ismapped .]} {
 		lappend cmd -parent .
@@ -25,7 +25,7 @@ proc warn_popup {msg} {
 	set cmd [list tk_messageBox \
 		-icon warning \
 		-type ok \
-		-title "$title: warning" \
+		-title [append "$title: " [mc "warning"]] \
 		-message $msg]
 	if {[winfo ismapped .]} {
 		lappend cmd -parent .
@@ -78,7 +78,7 @@ proc hook_failed_popup {hook msg} {
 		-font font_diff \
 		-yscrollcommand [list $w.m.sby set]
 	label $w.m.l2 \
-		-text {You must correct the above errors before committing.} \
+		-text [mc "You must correct the above errors before committing."] \
 		-anchor w \
 		-justify left \
 		-font font_uibold
@@ -99,6 +99,6 @@ proc hook_failed_popup {hook msg} {
 
 	bind $w <Visibility> "grab $w; focus $w"
 	bind $w <Key-Return> "destroy $w"
-	wm title $w "[appname] ([reponame]): error"
+	wm title $w [append "[appname] ([reponame]): " [mc "error"]]
 	tkwait window $w
 }