git-gui: Unify wording to say "to stage" instead of "to add"

Also, the warning message when clicking "Reset" is adapted to
the wording "Reset" rather than a confusion "Cancel commit?".

Signed-off-by: Christian Stimming <stimming@tuhh.de>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui.sh

@@ -1827,12 +1827,12 @@ if {[is_enabled multicommit] || [is_enabled singlecommit]} {
 	lappend disable_on_lock \
 		[list .mbar.commit entryconf [.mbar.commit index last] -state]
 
-	.mbar.commit add command -label {Add To Commit} \
+	.mbar.commit add command -label {Stage To Commit} \
 		-command do_add_selection
 	lappend disable_on_lock \
 		[list .mbar.commit entryconf [.mbar.commit index last] -state]
 
-	.mbar.commit add command -label {Add Tracked Files To Commit} \
+	.mbar.commit add command -label {Stage Changed Files To Commit} \
 		-command do_add_all \
 		-accelerator $M1T-I
 	lappend disable_on_lock \
@@ -2154,7 +2154,7 @@ pack .vpane.lower.commarea.buttons.rescan -side top -fill x
 lappend disable_on_lock \
 	{.vpane.lower.commarea.buttons.rescan conf -state}
 
-button .vpane.lower.commarea.buttons.incall -text {Add Tracked} \
+button .vpane.lower.commarea.buttons.incall -text {Stage Changed} \
 	-command do_add_all
 pack .vpane.lower.commarea.buttons.incall -side top -fill x
 lappend disable_on_lock \

lib/checkout_op.tcl

@@ -248,7 +248,7 @@ method _checkout {} {
 	if {[lock_index checkout_op]} {
 		after idle [cb _start_checkout]
 	} else {
-		_error $this "Index is already locked."
+		_error $this "Staging area (index) is already locked."
 		delete_this
 	}
 }

lib/commit.tcl

@@ -153,7 +153,7 @@ The rescan will be automatically started now.
 		U? {
 			error_popup "Unmerged files cannot be committed.
 
-File [short_path $path] has merge conflicts.  You must resolve them and add the file before committing.
+File [short_path $path] has merge conflicts.  You must resolve them and stage the file before committing.
 "
 			unlock_index
 			return
@@ -169,7 +169,7 @@ File [short_path $path] cannot be committed by this program.
 	if {!$files_ready && ![string match *merge $curType]} {
 		info_popup {No changes to commit.
 
-You must add at least 1 file before you can commit.
+You must stage at least 1 file before you can commit.
 }
 		unlock_index
 		return

lib/index.tcl

@@ -360,7 +360,7 @@ proc revert_helper {txt paths} {
 		"[appname] ([reponame])" \
 		"Revert changes in $s?
 
-Any unadded changes will be permanently lost by the revert." \
+Any unstaged changes will be permanently lost by the revert." \
 		question \
 		1 \
 		{Do Nothing} \

lib/merge.tcl

@@ -45,7 +45,7 @@ The rescan will be automatically started now.
 
 File [short_path $path] has merge conflicts.
 
-You must resolve them, add the file, and commit to complete the current merge.  Only then can you begin another merge.
+You must resolve them, stage the file, and commit to complete the current merge.  Only then can you begin another merge.
 "
 			unlock_index
 			return 0
@@ -219,16 +219,20 @@ You must finish amending this commit.
 	if {![lock_index abort]} return
 
 	if {[string match *merge* $commit_type]} {
-		set op merge
+		set op_question "Abort merge?
+
+Aborting the current merge will cause *ALL* uncommitted changes to be lost.
+
+Continue with aborting the current merge?"
 	} else {
-		set op commit
+		set op_question "Reset changes?
+
+Resetting the changes will cause *ALL* uncommitted changes to be lost.
+
+Continue with resetting the current changes?"
 	}
 
-	if {[ask_popup "Abort $op?
+	if {[ask_popup $op_question] eq {yes}} {
-
-Aborting the current $op will cause *ALL* uncommitted changes to be lost.
-
-Continue with aborting the current $op?"] eq {yes}} {
 		set fd [git_read read-tree --reset -u HEAD]
 		fconfigure $fd -blocking 0 -translation binary
 		fileevent $fd readable [namespace code [list _reset_wait $fd]]