Draw a terminal's label and its number apart, when asked to

A terminal's label is written as it is read off the plan, "X1:1", and
the symbol draws it as one field. On a long strip that field is long
enough to reach into the next terminal, and a user who wants the number
next to the screw and the label out of the way has no way to say so.

Settings > General > Appearance now has a "Display of the terminal
labelling" group with two choices: the label and its terminal number in
one field, the way it has always been drawn, or the two split. The
first is what every drawing gets, so nothing moves until the user asks
for it, and choosing the other one redraws the drawings already open --
nothing needs to be closed and opened again.

A symbol made for the split carries a text field bound to the new
"Terminal number" information (in the element editor's list, next to
the label, and as the %{terminal_number} variable of a composite text):
the label field then shows "X1" and the number field "1", each placed
where the symbol wants it, and hideable when it must be. A symbol which
has no such field -- every symbol drawn until now -- gets the number on
its own line inside the label field, so switching the setting on can
never make a number vanish, and never needs a symbol to be touched
first. A field which becomes, or stops being, the number field tells
the label fields of its symbol to draw themselves again.

Only the drawing reacts. What the element stores, the numbering, the
sorting in the terminal strip editor, the automatic strip import and
every export keep the whole label: the split is read where the text is
drawn (Element::labelForDisplay() and friends), not where the label is
made.

The new test covers both choices, with and without the number field, a
label with no colon at all, and the way back to the whole label. The
full test suite passes (124/124).

lang/qet_de.ts

@@ -6942,6 +6942,36 @@ Texte und Zahlen sind ebenso erlaubt.</translation>
         <source>Use gestures touchpad</source>
         <translation>Gesten vom Touchpad aktivieren</translation>
     </message>
+    <message>
+        <location filename="../sources/ui/configpage/generalconfigurationpage.ui" line="146"/>
+        <source>Display of the terminal labelling</source>
+        <translation>Darstellung der Klemmenbeschriftung</translation>
+    </message>
+    <message>
+        <location filename="../sources/ui/configpage/generalconfigurationpage.ui" line="152"/>
+        <source>A terminal's label (X1:1) is drawn as a whole, the way it has always been.</source>
+        <translation>Die BMK einer Klemme (X1:1) wird ganz gezeichnet, wie bisher.</translation>
+    </message>
+    <message>
+        <location filename="../sources/ui/configpage/generalconfigurationpage.ui" line="155"/>
+        <source>Show the label and the terminal number in one field</source>
+        <translation>BMK (Label) und Anschlussnummer in einem Feld anzeigen</translation>
+    </message>
+    <message>
+        <location filename="../sources/ui/configpage/generalconfigurationpage.ui" line="165"/>
+        <source>The label (X1) is drawn in one field and the terminal number (1) in another, which a terminal symbol may place where it wants -- and hide when it must. A symbol without such a field shows the two, one under the other.</source>
+        <translation>Die BMK (X1) wird in einem Feld und die Anschlussnummer (1) in einem weiteren Feld gezeichnet, das ein Klemmensymbol platzieren kann, wo es will -- und ausblenden, wenn es muss. Ein Symbol ohne ein solches Feld zeigt beides untereinander.</translation>
+    </message>
+    <message>
+        <location filename="../sources/ui/configpage/generalconfigurationpage.ui" line="168"/>
+        <source>Split the label and the terminal number</source>
+        <translation>BMK und Anschlussnummer auftrennen</translation>
+    </message>
+    <message>
+        <location filename="../sources/ui/configpage/generalconfigurationpage.ui" line="175"/>
+        <source>Only the drawing changes: what is written in the element, the numbering, the sorting and the exports keep the whole label.</source>
+        <translation>Es ändert sich nur die Darstellung: Was im Bauteil steht, die Nummerierung, die Sortierung und die Exporte behalten das ganze Label.</translation>
+    </message>
     <message>
         <location filename="../sources/ui/configpage/generalconfigurationpage.ui" line="297"/>
         <source>Use sheet numbers instead of their position in the project</source>
@@ -16677,6 +16707,11 @@ Möchten Sie sie ersetzen?</translation>
         <source>Label</source>
         <translation>Betriebsmittelkennzeichen (BMK)</translation>
     </message>
+    <message>
+        <location filename="../sources/qetinformation.cpp" line="315"/>
+        <source>Terminal number</source>
+        <translation>Anschlussnummer</translation>
+    </message>
     <message>
         <location filename="../sources/editor/graphicspart/partplctable.cpp" line="189"/>
         <source>PLC Table</source>