[ReqAnalyzer] Odd-looking times in countertraces when using prev

[alopez-developair]

As mentioned in #543, this would apply to 6d31cd0, as more recent versions don't show these inconsistencies.

Example:

Input count_1 is int

R11: Globally, it is always the case that "count_1 == prev(count_1) + 1" holds at least every "1" time units.
R12: Globally, it is never the case that "count_1 < prev(count_1)" holds.
R13: Globally, it is never the case that "count_1 < 0" holds.
R14: Globally, it is always the case that if "count_1 == 0" holds, then "count_1 >= 10" holds after at most "10" time units.

Result:

- ReqCheckRtInconsistentResult [Line: -1]: Requirements R14, R11 are rt-inconsistent
    Requirements R14, R11 are rt-inconsistent
We found a FailurePath: 
INITIAL      |'count_1|=0 count_1=0
[0;17/2]     |'count_1|=0 count_1=1
[17/2;17]    |'count_1|=1 count_1=1

Without going too much into other specifics of the example, in this issue I want to address the following:

• Initial value for count_1 is 0. Thus, via R14, count_1 >= 10 will have to happen before time 10.
• During [0;17/2] (i.e. 0-8.5), count_1 = 1 and prev(count_1) = 0, satisfying R11.
• And the last segment [8.5;17] is the one that I can't make heads and tails of:
  • count_1 == prev(count_1) for 8.5 units, which seems to violate R11.
  • The time point 10 has been crossed and count_1 == 1so R14 is also being violated in this example.