plugin: Obtain param default value on initParameter()

During plugin initialization, we can directly invoke CCetoneSynth::getParameter() to get  default parameter value, as at that time only the default program is loaded.

src/CetoneSynthDPF.cpp

@@ -7,7 +7,7 @@ void CCetoneSynth::initParameter(uint32_t index, Parameter& parameter)
     // Fallback to classic VST 2.4 param range (0.0 ~ 1.0), to fit with Cetone's own param handlers.
     parameter.ranges.min = 0.0f;
     parameter.ranges.max = 1.0f;
-    parameter.ranges.def = 0.5f;
+    parameter.ranges.def = getParameter(index);
 
     // Must set parameter.symbol, this is the unique ID of each parameter.
     // If not set, you can neither save presets nor reset to factory default, in VST3 and CLAP!