Bug 730980: GIMP enters an infinite loop loading a truncated xcf

(cherry picked from commit fe4502fe0410b25dfac999daad3127263bae7e0d)

Conflicts:
	app/xcf/xcf-load.c
Bug 730396: GIMP crashes loading a XCF it saved

add few validity checks loading a xcf file.

(cherry picked from commit a64a319d78455a13d51fc7983fa18ce7ce5549d8)

Conflicts:
	app/xcf/xcf-load.c
app: xcf-load fix app/tests/test-xcf

though it crashes loading corrupt files
Bug 731389 - gimp-edit-copy causes assertion failure on exit

Shutdown the clipboard earlier at exit, it runs quite some code on
storing the copied buffer.

(cherry picked from commit 8aa6ff9608aa497c1b394dace50c99216b1cd995)
Bug 729789 - Exporting to .xjt file creates multi GB file

Disable saving of XJT files for the same reasons the plug-in
got removed entirely in master.
pygimp: Layers retrieved using "parent" have to be GroupLayers

    Thanks Seldom Needy for spotting this.

(cherry picked from commit f7e1dd2501db4ae7201e225a9b54c5b1e168c9cb)
Updated Spanish Translation
Bug 731765 - "Value Propagate" dialog's "Propagating rate" spinbuttons...

...are much too quick

In gimp_scale_entry_new(), set the spinbutton's climb_rate to the same
value as step_increment instead of hardcoding 1.0. This should make
many spinbuttons behave better.

(cherry picked from commit b9265ebfb9166d2819d21410740c44ffad0f1682)
Bug 731362 - Merging layers (outside layer folders)...

...causes layer folders to expand

In gimp_image_remove_layer(), don't use the top element of
image->layer_stack as the new active layer, because it is simply some
arbitrary layer that was previously selected. That stack is only good
for finding the last active layer when returning from the channels
dialog. Instead, let the proper logic run and use the new active item
returned by gimp_item_tree_remove_item(), which is the layer below the
removed one, if any, or the one above it otherwise.

(cherry picked from commit 0e2b8f236d6bdb953439ee229e84e22e58b636aa)
Updated Greek translation
Updated Greek translation
Updated Greek translation
Bug 727854 - Export file type should not be based on filename extension

Keep the export proc acound in the image (just as we keep around
the save proc), and use it when exporting again.

(cherry picked from commit 3dbae5e4d97139b7917c229671fe90963ab7d0e6)
Updated Dutch translation 2-8
app: fix handling of guides and sample points in gimpimage-resize.c

Don't iterate the lists with for() because the loops can remove items,
which makes us say g_list_next() on a removed list item. Instead, use
while() and get the next item before possibly removing the current
one.

(cherry picked from commit 99ccf7223b1aafdc7bc07b37eb8497ccc2912dab)
Bug 732163 - Flipped pixel columns in TGA

do not flip the central columns twice

(cherry picked from commit 35466d6dd0cceaff29109424f6fb94abf1807956)
Minor cosmetic cleanup: fix C style comments

Replace C++ and Java style comments by C style comments.
Improve OSX build instructions

Add note about XCode,
add file descriptions,
fix broken links,
fix curl parameters,
add structure,
improve wording,
improve layout.
OSX bundler: fix link to .plist file

Refer to info-2.8-python.plist instead of info-2.8.8-python.plist.
OSX bundler: make launcher more generic

Rename the launcher to launcher-python.sh to make it also usable for
GIMP-master.