(std::stoi ignores subsequent symbols)

and add missing function declaration

(this is still a bit hacky)

ModuleWidget respond to Backspace/Delete only if no widget is focused

the macro VERSION_0_4_0

to Midi-to-CV and add Midi-CC-to-CV

Ref: https://github.com/VCVRack/Rack/issues/122

Xcode-cli tools no longer enough...?

```
checking for nanosleep... yes
xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance
```
(https://github.com/VCVRack/Rack/issues/122)

(Note: WIP, did not test build on windows/mac)