Per http://dev.mysql.com/doc/refman/5.7/en/numeric-type-overview.html
`BOOL` and `BOOLEAN` is alias for `TINYINT(1)` thus we should make
sure discover can handle as such.
Introducing three flags:
* treatCHAR1AsString
default false - treats CHAR(1) as a String instead of a Boolean
* treatBIT1AsBit
default true - treats BIT(1) as a Boolean instead of a Binary
* treatTINYINT1AsTinyInt
default true - treats TINYINT(1) as a Boolean instead of a Number
The default handling for CHAR(1) is legacy backward compability due to
custom to use a CHAR(1) to store 'Y', 'N', '0', '1', etc...
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