[[ ImageLoader ]] Create MCImageLoader class interface
[[ ImageLoader ]] Reimplement MCImageDecode<format> functions as equivalent MCImageLoader subclasses
[[ ImageLoader ]] Update Image import functions to use MCImageLoader
[[ ImageLoader ]] Fix bug in IO_fgets causing inifinite loop when loading xpm file
[[ ImageLoader ]] Update Android, iOS, Linux & OSX server build files
[[ ImageLoader ]] Update Windows engine & server build files
Merge remote-tracking branch 'runrevian/refactor-imageloader' into bugfix-13021

Conflicts:
	engine/engine.xcodeproj/project.pbxproj
	engine/src/ifile.cpp
	engine/src/igif.cpp
	engine/src/iimport.cpp
	engine/src/image.h
	engine/src/image_rep_encoded.cpp
[[ Bug 12852 ]] Make sure we use the converted value of the input from the EP rather than the original value when setting labels of buttons.
Merge branch 'bugfix-12852' into release-6.6.3
[[ Bug 13021 ]] Rework MCImage::lockbitmap() MCImage::draw() to allow density-mapped images to have mismatched scale & image sizes.
[[ Bug 13021 ]] Modify MCDensityMappedImageRep::GetGeometry() to return logical image size for the whole set.
[[ Bug 13021 ]] Remove unused density & scale methods from MCImage & MCImageRep classes
[[ Bug 13021 ]] Add MCGRectangleScale variant with horiz/vert params
[[ ImageLoader ]] Add frame count to information read from the header.
[[ ImageLoader ]] Use header framecount for MCEncodedImageRep::GetFrameCount()
Merge remote-tracking branch 'runrevian/refactor-imageloader' into bugfix-13021

Conflicts:
	engine/src/ibmp.cpp
	engine/src/igif.cpp
	engine/src/ijpg.cpp
	engine/src/image_rep.cpp
	engine/src/image_rep.h
	engine/src/imageloader.cpp
	engine/src/ipng.cpp
[[ Bug 13021 ]] Add bugfix note
[[ Bug 13058 ]] Use Stack view rect when determining if pointer is still within stack window
[[ Bugfix 13065 ]] making selection with shift + click player thumb
Added bugfix note
Merge branch 'bugfix-9941' into release-6.6.3
Merge branch 'release-6.6.3' into develop
[[ Bug 13098 ]] Don't synthesise a key event for composition sequences, just use direct insertion.
Merge branch 'bugfix-13098' into develop
[[ Bugfix 13105 ]] Player: Make sure currenttimechanged message is sent when stepping forward/backward