add log message MOAI_FileOpenError_S

While this may seem redundant with MOAI_FileNotFound_S, there
may be cases where the file exists but can't be opened, e.g.,
due to permission errors. This also supports a safer code structure:
actually try to open the file and log if it fails, instead of checking
for file existence and then just assuming it will open.
use MOAILogMessages::CheckFileExists instead of USFileSys::CheckFileExists so we get an error message
Log if file didn't open successfully
check and log if sound file doesn't exist

I would have preferred to check whether the actual file-open
operation succeeded, but this would require adding a check inside
untz itself, which doesn't have a clear logging mechanism at
the moment.
- Camera support for iOS on moai
- Fixed not dimissing picker
Adding file not found log if a texture file fails to load
Fixing build errors for DataTaskIO
fix: MOAIImageTexture not override OnInvalidate
Merge pull request #619 from antback/master

Initial Camera Support for iOS
Merge pull request #618 from tommo/bug-fix

fix: MOAIImageTexture not override OnInvalidate
Merge pull request #592 from sporksmith/log-file-open-fails-pull-req

Log file-open failures
Merge branch 'moai-dev/master'
Fixing issue with setting visibility not properly updating dependencies
Fixed VSYNC issue for OSX host.
Merge pull request #621 from clementfarabet/master

Fixed VSYNC issue on OSX.
VSYNC fix is for Apple only.
Merge pull request #622 from clementfarabet/master

VSYNC fix is only for OSX.
[Fixed Bug] NaCl won't build

Due to some commits NaCl Broke.
Here are some changed needed to make it work again.

Moved US* to MOAI* as in moai/moai-dev@9c39f367f3bd26d6c3c9ccf0d636c85338cdcfa9
Added MOAITaskQueue and MOAITaskSubscriber as in moai/moai-dev@c8c863f511ee43626fa1935b3176e39f65f002c1
Removed MOAIData.cpp since was deleted in moai/moai-dev@e682da1ae8b93deccee6e03ceac0cc3c19f415a2
Removed MOAIDataIOAction.cpp since was deleted in moai/moai-dev@c8c863f511ee43626fa1935b3176e39f65f002c1
Sorted commas to match a single column.
[Fixed Bug] Visual Studio 2010 won't build

Due to some commits Visual Studio 2010 build broke.
Here are some changed needed to make it work again.

Moved US* to MOAI* as in moai/moai-dev@9c39f36
Added MOAITaskQueue and MOAITaskSubscriber as in moai/moai-dev@c8c863f
Removed MOAIData.cpp since was deleted in moai/moai-dev@e682da1
Removed MOAIDataIOAction.cpp since was deleted in moai/moai-dev@c8c863f