Scoverage targets invalidate incremental compilation

[lolgab]

Compiling with coverage enabled is not compatible with normal compilation without coverage.
This makes all incremental compiler cache to be invalidated when you switch back and forth to coverage.
A possible solution to this problem is to store coverage compilation targets in a separate directory (scapegoat does this, for example).

[lolgab]

I found a workaround that works well enough for me.
I added this setting to all the modules in my build:

target := { if (ScoverageKeys.coverageEnabled.value) target.value / "coverage" else target.value }

This way I create a separate target directory when coverage is enabled and I can switch back and forth without having to recompile everything over and over again.