refactor(editor): the helpers repeated over the editor files are shared

The name of a node or "(no name)" was written out in twenty places and
four local functions, a lower-case copy of a text in four files, the
test for a number, the file name of a template made comparable and the
heading of a direction in three and two, the green main button of a
panel in five and the key=value parameters of a self-test command in
five. Each of them is one helper now: name_of, tall_button_height and
main_button with the panel helpers, numeric with format, normalized
with the include helpers, heading_of with the plan geometry and
selftest_values with the tools; lower gives way to ToLower.

application/editormodetrackprops.cpp

@@ -57,11 +57,6 @@ bool rail(TTrack const &Track)
 	return (Track.iCategoryFlag & 15) == kRailCategory && false == Track.m_editorremoved && Track.visible();
 }
 
-std::string name_of(TTrack const &Track)
-{
-	return Track.name().empty() ? std::string{STR_C("(no name)")} : Track.name();
-}
-
 char const *type_of(TTrack const &Track)
 {
 	switch (Track.eType)