Do small vector optimization for all communication

I once read years ago somewhere on Stack Overflow that `std::vectors`
with that are preinitialized to a default size would allocate the
initial capacity on the stack. This of course doesn't make any
sense (run time sized stack allocations can cause all kinds of issues),
so we were still allocating with our default 64-byte sized buffers, but
just not as often.

CHANGELOG.md

@@ -40,6 +40,9 @@ Versioning](https://semver.org/spec/v2.0.0.html).
   event and parameter change queues.
 - VST2 audio processing also received the same small vector optimization to get
   rid of any last potential allocations during audio processing.
+- The same small vector optimization has been applied across yabridge's entire
+  communication architecture, meaning that most function calls should no longer
+  produce any allocations for both VST2 and VST3 plugins.
 - Changed the way mutual recursion in VST3 plugins on the plugin side works to
   counter any potential GUI related timing issues with VST3 plugins when using
   multiple instances of a plugin.