improve Mic/Aux rack, equalize layout spacing#13

Be-ing merged 2 commits intoBe-ing:deere_2.1_part_2Be-ing/mixxx:deere_2.1_part_2from

ronso0:deere_2.1_update_MicAuxronso0/mixxx:deere_2.1_update_MicAuxCopy head branch name to clipboard