FLTK 1.4.x release candidate

Enabling the untested "wayland" option should (in theory) allow to use
the new Wayland backend.

The option "cairo" enables support for the widget Fl_Cairo_Window.

Glyph substitution via Pango with X11 backend is now supported.
The "pango" option allows applications to render text using multiple fonts.

Disabling the "pango" and "xft2" options allows to use X11 Core Fonts
(rendered by the X server). Works well with network redirection of DISPLAY.
This is for users who want the "F" in FLTK.

Disabling the "xcursor", "xfixes", "xinerama" and "xrender" options allows
to further reduce dependencies for the X11 backend.
This is for users who want the "L" in FLTK.

In general applications using the FLTK 1.3 API should work out-of-the-box
with FLTK 1.4 too. Note: The ABI of the shared library is not compatible!


Note:
FLTK 1.4 will be the last release that supports old systems (C99 / C++98).
The next release of FLTK will require at least C++11 and CMake. This will
drop more than a decade of formerly supported systems.
