Be able to split sentences

[jecarr]

Sometimes a single sentence in Thread is actually multiple sentences. We should be able to allow the user to specify a point where to split a sentence and create a new sentence object from that index/position.

Given a sentence, x, "This is my single Thread sentence. Look how there's actually another sentence."

I should be able to split at position 34, trim both strings and now have

x1 = "This is my single Thread sentence."
x2 = "Look how there's actually another sentence."

All sentence-index values beyond x's are then incremented by 1.

If x originally had TTPs mapped to it, it should be duplicated and saved against x1 and x2. Same with an IoC.