The Model was getting unmaintanable mess. This is an attempt to refactor/rewrite the Model so that data of certain type is exposed in standardized way, offering certain standard manipulations for that data type, and on the GUI side, certain standard widgets to tied to that data.
This rewrite closes#72, #106 and #120.
The Render name misleading as it did not do the same thing as normal
Synth.Render, because it disregarded time limits. Conceptually, as
the function modifies the state of the synth, it would be better to
be synth.Fill(audioBuffer), but we cannot define methods on
interfaces; therefore, it is audioBuffer.Fill(synth) now.
Throughout sointu, we assume stereo audiobuffers, but were passing
around []float32. This had several issues, including len(buf)/2 and
numSamples*2 type of length conversion in many places. Also, it
caused one bug in a test case, causing it to succeed when it should
have not (the test had +-1 when it should have had +-2). This
refactoring makes it impossible to have odd length buffer issues.
send targets are now by ID and Song has "Score" part, which is the notes for it. also, moved the model part separate of the actual gioui dependend stuff.
sorry to my future self about the code bomb; ended up too far and did not find an easy way to rewrite the history to make the steps smaller, so in the end, just squashed everything.
