build/win: Tweak gtk2 hack
app: port gimpconfig-dump.c to GIO
app: port gimp_interpreter_db_resolve() to GIO
app: move memsize functions into their own files gimp-memsize.[ch]
configure.ac, INSTALL.in: remove traces of libcurl and the URI plug-in

and fix formatting of "Summary of optional packages" in INSTALL.in
configure.ac, *: require GLib 2.40.0

Remove gimp_output_stream_[v]printf() and use the new functions from
GLib instead. Use memmove() instead of the deprecated g_memmove().
app: don't use GLIB_CHECK_VERSION (2, 39, 90) for win32 argv parsing

Instead, use the new APIs unconditionally.
Do not use g_io_channel_unix_new() for the win32 platforms.

It is advised to use the more accurate g_io_channel_win32_new_fd() or
g_io_channel_win32_new_socket() because GLib can't differentiate between
file descriptors and sockets on Windows, which outputs a warning when
there is ambiguity.
INSTALL: wrong list numbering.
Bug 733525: check presence of poppler-data (informational only).

As of version 0.4.7, poppler-data has a pkg-config file, allowing us to
verify its presence. The configure summary is only informational, and we
don't impose this version since older versions may still work.
Moreover poppler-data is only a runtime dependency, so you can also add
it afterwards.
Fix generation of AUTHORS

scl tried to modify AUTHORS in 4f852593, but he didn't realize it's
an autogenerated file. This is just repeating his changes on
authors.xml so it matches the modified AUTHORS.
build/win: Upgrade poppler to 0.26.3
plug-ins: move file-compressor to plug-ins/common/, it's only one .c file
build/win: Upgrade harfbuzz to 0.9.34
build/win: Upgrade pixman to 0.32.6
Bug 734705 - v2.9.1 crashes when scaling an image in indexed colors mode

Use gimp_image_get_format() instead of gimp_babl_format() in
gimp_drawable_real_estimate_memsize() because the latter can't handle
indexed formats and returns NULL.
build/win: Upgrade pango to 1.36.5
tests: build the test icon theme for all platforms.

In particular, we were not building these for win32, which has no
symbolic link concept. So let's use $(LN_S) defined by autoconf for this
purpose, as it will copy files for platforms without ln support.
Moreover this way, we don't create one such folder for each and every
test run and fill up the tmp directory with countless directories, that
we never clean up.
On Win32, this fixes 3 tests which were failing because of the missing
icons.
tests: gimp_test_utils_synthesize_key_event() not working for win32.

gdk_test_simulate_key() has currently no win32 implementation.
Add this implementation in our code until a patch to GTK+ for this is
merged. This fixes 2 `make check` tests for win32.
tests: make warnings non fatal for tests on win32.

g_test_init() makes any warning message fatale by default. While it
makes sense for the main OS that we build on (Linux), I believe that
our tests on Windows are more useful when they finish, even with some
warnings, than stopping because some stupid font warning would occur
(case I encountered, did not know the solution of, and is not really
relevant to the rest of the test).