A Pair action inserts a pair of characters (left and right) around the
current selection, and then places the caret between them
The pairs are hard-coded here.
the pair value to use if this token is one of a pair:
This is how it is used:
The openning part will have a positive number X
The closing part will have a negative number X
X should be unique for a pair:
e.g. for [ pairValue = +1
for ] pairValue = -1
Parses a query in KReator's unified-syntax from a string
i.e. a querying atom expression (possibly) conditioned by several evidence atoms expressions,
whereas the constants must begin with a lower-case character.