Since we're using OpenGL, everything has to be done in the same thread anyways. Besides that, the actual "multithreading" implementation was basically starting an empty thread that did absolutely nothing, then wait synchronously for it to complete and join it on the next frame.
Also gets rid of the dirent.h hack used on Windows platforms, as the filesystem API hides all the OS-specific stuff, and we can use a recursive iterator instead of doing that ourselves, making the code even cleaner.
This did not have any real impact, as the excess bytes were written into the next buffer, which was then immediately "fixed up" during the following copy call with the correct data, but could cause a crash and other nasty things if someone would reorder the class members or insert something in between.
The HLSLMacro struct is manually malloc'd, not using new/delete, so the std::string destructor is never called on the instance stored in the class.
Fixed by using a char* allocated by HLSLTree, which will then properly take care of deleting it after parsing is complete.
Waveform code was kindly provided and used with permission by Milkdrop2077.
Had to make a few amends though, as some sample offsets went over the allocated waveform sample count (>480), leading to memory issues.
Instead of using these expressions, adding "lib" in fron of static libs is now done via CMAKE_STATIC_LIBRARY_PREFIX when building static libs on Windows.
WebGL doesn't follow the OpenGL standard format for the glGetString(GL_SHADING_LANGUAGE_VERSION) return value. Chrome for example will return "OpenGL ES GLSL ES 3.00 (WebGL GLSL ES 3.00 (OpenGL ES GLSL ES 3.0 Chromium))", which does not start with the version number as the standard suggests.
This fix will simply cut off any text preceding the first digit found in the string, if any.
Consolidated audio processing code into the PCM class, removing the BeatDetect class in the process. Beat detection now uses the same algorithm as Milkdrop, passing the proper relative bass/mid/treb values to presets. Makes many presets look less jumpy/flickering, as the values are now (smoothly) alternating around 1.0.
Updating frame audio is now done in a function that must specifically be called. Any subsequent calls to GetFrameAudioData() will then return the exact same copy of the audio data. As of now with the exception that new waveform data may be passed in via a separate thread, which will then be returned and might not match the spectrum data. Will fix that in a later commit.
Removed the previous FFT algorithm, now using a modernized version of the original Milkdrop FFT transform which also has both an equalizer and frequency envelope, making it slightly more sophisticated.
Modernization mainly included replacing raw pointer arrays with std::vector and using STL types/functions for the calculation, specifically std::complex as the FFT heavily uses these numbers. This makes the code more compact and readable.
Manually tested both original and modernized versions of the class to test if the algorithm still returns the exact same results, which is the case.
