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.

editor/editorFormat.hpp

@@ -10,6 +10,7 @@ http://mozilla.org/MPL/2.0/.
 #pragma once
 
 #include <cstdio>
+#include <cstdlib>
 #include <string>
 
 // printf-style formatting into a string, for the messages and the data lines of the editor
@@ -24,3 +25,10 @@ std::string format(char const *Format, Args... Arguments)
 	text.resize(static_cast<std::size_t>(length));
 	return text;
 }
+
+inline bool numeric(std::string const &Text, double &Value)
+{
+	char *end{nullptr};
+	Value = std::strtod(Text.c_str(), &end);
+	return false == Text.empty() && *end == '\0';
+}