ofxTimeline without any dependency on ofxAudioDecoder + minor fixes and updates

[hsab]

This is a fork of ofxTimeline without any dependency on ofxAudioDecoder. As a result there is no support for mp3 files.
I spent hours trying to get ofxAudioDecoder to compile properly, however the provided example did not behave as expected once no errors where thrown. Furthermore upon inspection of ofOpenALSoundPlayer_TimelineAdditions, the only instance of ofxAudioDecoder is found in decoderReadFile function which is only called when the file format is mp3.
I've been successfully able to compile the allTracks example on Windows 10 using VS2015.

Changes:

• Removed ofxAudioDecoder dependency.
• Cleaned up ofOpenALSoundPlayer_TimelineAdditions class by removing unused methods and code.
• Updated OpenAL libs and dlls to latest version 1.1.
• Fixed switch and flag tracks' text input field as suggested here.

Installation:

You need the following dependencies:

• ofxMSATimer
• ofxRange
• ofxTextInputField
• ofxTimecode
• ofxTween
• ofxXmlSettings

On Windows:

• Make sure that you are using K-Lite Codec Pack 12.1.0 Full ~ 33.9 MB ~ April 18th 2016 for video compatibility as suggested here.
• Copy the the appropriate architecture dependent dlls from dll folder to you app's bin folder.

For all platforms:

• Copy GUI folder to your app's bin/data folder.