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.
Merge remote-tracking branch 'official/master'

Conflicts:
	src/CaseContent/Conversation.cpp
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 remote-tracking branch 'official/master'

Conflicts:
	src/FileFunctions.cpp