Improve Text Selection Mechanics

[mhbeals]

Current text selection mechanic is fiddly.

Last Word Error:

• Fixed "last word" bug where the counter goes to -1 when finding a selection including the last word of the item (Fixed 0.3.8)

Repeated Text Error:

Sometimes a selection of text might appear multiple times in an item. Currently the heuristic just looks for the first instance of the phrase. To make this more robust, we need to have a better indexing system:

• Change find exact word in location
• Count spaces before exact word for start word number
• Count spaces in text selection for end word number