Add more aggregation operators to NoSQL.

The following operators have now been added:

$binarySize

$indexOfBytes

$indexOfCP

$ltrim

$reverseArray

$rtrim

$slice

$split

$strCaseCmp

$strLenBytes

$strLenCP

$substr

$substrBytes

$substrCP

$toLower

$toUpper

$trim

$trunc

Initially the intent was to add string and date operators, but a decision was made to focus on the former and to leave all date-operators to a later stage. In addition to the string operators, a number of other trivial operators were added as well.