Import Yuri's screenshot to use by desktop/fontforge.appdata.xml

Removed extra </p>, then moved other </p>s
Change URL for fontforge.appdata.xml to more readable pointer
Remove osx Makefile wildcard *.nib warnings during bootstrap

Seen repeatedly in issues that complain of bootstrap and autogen.sh
Remove osx Makefile wildcard *.cns warnings during bootstrap

Seen repeatedly in issues that complain of bootstrap and autogen.sh
bootstrap defaults to using the config directory

moved config.guess and config.sub into subdirectory config because
bootstrap defaults to using the config directory.

NOTE: configure.ac requires AC_CONFIG_AUX_DIR(a_directory) for bootstrap.
Update config.guess and config.sub to latest --HEAD
New Authors/Developers added that contributed during 20140101 to now.
Ensure pkg-config is installed, and warn developers of /usr/local

pkg-config is required for installing *.pc files in /usr directory.
configure.ac calls pkg-config in several places to find packages.
NOTE: Several distros default behaviours skip looking in /usr/local
since they are not configured this way when the distro is installed,
therefore, you many users will not likely find programs/libraries
built/installed by the user (default build destination="/usr/local".
PKG_PROG_PKG_CONFIG() >= version 0.25
osx MainMenu.nib directory a little different - needs different Makefile

Fix error in patch discovered by travis (part of dist check).
Merge pull request #1392 from JoesCat/homebrew_and_1366

Homebrew and issue#1366