Most MQ tables contain columns like 'contaminants' or 'reverse', whose values are either empty strings
or "+", which is inconvenient and can be much better represented as TRUE/FALSE.
The params valid_entries and replacements contain the matched pairs, which determine what is replaced with what.
Name of the column (e.g. "contaminants") in the mq.data table
Vector of values to be replaced (must contain all values expected in the column -- fails otherwise)
Vector of values inserted with the same length as valid_entries.
Returns TRUE if successful.