Truly maximize w32 frames with odd fonts and some texi fixes.

* w32fns.c (w32_wnd_proc): For WM_WINDOWPOSCHANGING don't
constrain frame size in SW_SHOWMAXIMIZED case so we can truly
maximize a frame for odd default fonts.
* frames.texi (Size and Position): In `frame-resize-pixelwise'
description drop remark about frame maximization.
* windows.texi (Display Action Functions): Add description for
`display-buffer-no-window' and explain use of `allow-no-window'
alist entries.