More consistent naming conventions for choice control items...

... This commit leaves at least a comment for all choice controls of all
built-in effects and commands.

Use CamelCase with no spaces for the internal identifiers, given in
wxT("...")

Use more idiomatic English with spaces in the user-visible names, given in
XO("..."); these strings go to the message catalog for internationalization

Do not use underscores

In case these strings are the same, give it just once in XO("..."), but if in
a future version it is decided to change the name in XO("..."), then the
original should be kept also in a distinct wxT("...") string, so that
saved configuration or plugin settings or macro files don't become gratuitously
incompatible just because of that user-visible name change.

Left TruncateSilence alone for now -- I think that choice demands a rewrite
as a slider instead.

src/commands/DragCommand.cpp

@@ -41,9 +41,9 @@ enum kCoordTypes
 static const IdentInterfaceSymbol kCoordTypeStrings[nCoordTypes] =
 {
    { XO("Panel") },
-   { XO("App") },
-   { XO("Track0") },
-   { XO("Track1") },
+   { wxT("App"),    XO("Application") },
+   { wxT("Track0"), XO("Track 0") },
+   { wxT("Track1"), XO("Track 1") },
 };