Support persist-params-after-send

Add persistRcValuesButt to allow mappings to be persisted outside the
calibration mode; cleanup const params in param dataq model;  add some
debug for mapping problems
persist params immediately after we know that we've send all pending
allow identification of 8 channels during calibration

Add "skip" buttons in msg box (instead of cancel); allow user to cancel
upload of rc params after reviewing them
Merge pull request #338 from tstellanova/config_debug

RC calibration and mapping debug