* fnkeys.tes has been updated to enable the command line
   editing macros (cursor keys, etc.) only in the "start" state.
   This avoids the annoying effect of inserting the macros
   into string arguments where they have no effect and must be
   rubbed out again.

 * It is still useful to have this in macros since you may want to
   work with non-normalized file names.
   For instance, env variables (including $SCITECOPATH and $SCITECOCONFIG)
   may (and will probably) include backward-slash separators on Windows

 * on Windows, this register contained backward slashes. This means
   that macros working with that register had to cope with both
   forward and backward slashes.
 * The file names are still displayed in the native style by the UI
 * This approach also has disadvantages: What if the user wants
   to insert the current file name somewhere where "\" is expected?
   However, this seems to be an unlikely case and the use can still
   replace the "/" with "\" again.
 * Avoid some virtual method calls in QRegisterBufferInfo

this looks better in Unicode terminals

 * for historic reasons, the backspace key can be transmitted as
   ^H by the terminal. Some terminal emulators might do that - these
   are fixed by this commit.
 * Use CTL_KEY('H') instead of standard C '\b' as the former is less
   ambiguous given the confusion around the backspace character.

 * the ^I command was altered to insert indention characters
   rather than plain tabs always.
 * The <TAB> immediate editing command was added for all
   insertion arguments (I, ^I but also FR and FS)
 * documentation was extended for a discussion of indention

 * this is actually UNTESTED on Windows

 * pressing e.g. TAB when the popup is showing a list of auto-completions
   will show the next page, eventually beginning at the first one again.
 * do not redraw curses windows in the UI methods directly. this resulted
   in flickering during command-line editing macros and ordinary macro calls
   because the physical screen was updated immediately.
   Instead, window refreshing and updated is done centrally in
   event_loop_iter() only after a key has been processed.
   Also we use wnoutrefresh() and doupdate() to send as little to the
   terminal (emulator) as possible.