Switch to DISTRHO/juce for LV2 support

[fpesari]

Hi,

ISSE could use DISTRHO/juce fork of JUCE so that it can be used as a LV2 plugin.

[jpcima]

Hi, this porting effort is not complete, and I need to come back to it when I am able to dedicate some time on it. It was on a request to update it to modern standards, considering code is very outdated.

It's made able to compile with a moderately recent Juce, but audio IO is non working. Probably, in relation with audio graph stuff, since it's the part most affected during the porting.

So, before all things, it's needed to get the program working.