Memory improvement regarding Dialog objects

Fixed an issue where we were creating the Dialog object in
ShowDialogAction::Begin(), but were not deleting it in its counterpart,
ShowDialogAction::Reset().  This caused us to start to progressively eat
up more and more memory as more and more Dialog objects were left
undeleted.
Skip Unix hidden files that begin with a period.
Use FileSystemRepresentation when possible on OS X:
This function returns a c-string that IS safe to pass to low-level file functions, like open.
Better file handling on OS X.
OS X: add a few autorelease pools.
Fix an over-release bug.
OS X:
Only return the number of actual elements in the array.
Added the ability to skip not-yet-seen dialog

NOTE: This requires the common.dat in v1.0.1 of MLI to function
properly.  Don't sync to this revision until you've downloaded that
through the updater.

Added a toggle button in the options menu to enable players to opt to be
able to skip dialog that they haven't seen yet.
Fixing text caret issue

Everything drawn in MLI goes through the Image class, which takes the
game surface resolution into account - except for the caret in prompt
overlays, which is just drawn as a rectangle.  This fixes things by
making the caret take the screen scale into account as well.
Fixing uninitialized variable in DialogCharacter::OneTimeEmotion

leadInTime in DialogCharacter::OneTimeEmotion, if it doesn't exist in
the XML definition, never actually gets initialized to anything.  We
should initialize it to 0.  (Thanks to cabbage, who pointed this out on
the forums.)
Merge pull request #10 from MaddTheSane/backToGabu

OS X fixes and optimizations
Fixing merge

Fixing what looks like a bad merge for the OS X stuff that caused a
build break.
Fixing a crash in ShowDialogAction

The previous change to delete pDialog has an edge-case it brought to
light where we were expecting pDialog to still exist even though we're
not actually really doing anything with it.  We should make
ShowDialogAction resilient against a NULL pDialog and not crash if it's
NULL.
Merge branch 'master' into arch-release
Merge remote-tracking branch 'official/master' into arch-release

Conflicts:
	src/CaseContent/Conversation.cpp
	src/FileFunctions.cpp
Merge branch 'master' into arch-release
Customizable common-data dir in cmake
remove spaces in .desktop name