Uncovered edge cases in executable model

There are a few uncovered edge cases for the executable model in the following 2 area:

1. accumulate
a. a specific issue when using dialect mvel + legacy syntax + global
b. use of existential pattern inside accumulate

2. CEP
a. dynamic timestamp/duration, e.g.: @timestamp( getProperties().get( 'timestamp' ) - 1 )
b. dynamic timer, e.g.: timer (int: 0 1; start=$startTime, repeat-limit=0 )
c. temporal comparison of an event and a date field of another fact, e.g.: Event( this after $other.date )
d. it is not possible to use a temporal constraint in || with another constraint

This ticket is to backport the implementation of these features on the 7.11.x branch