add moveLeftHandle and moveRightHandle methods

[brendanlensink]

Fixes #17

Adds the moveLeftHandle and moveRightHandle methods to the TrimmerView.
It's worth noting this will allow you to set the right handle to the left of the left handle and vice versa if you aren't careful, not sure if this is something you'd like to handle or not.

[ghost]

DeepCode analyzed this pull request.
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[HHK1]

Thank you for contributing ! There is another PR (#41) trying to add the same functionality, and I believe that the same thing is missing in your contribution.
On top of moving the left and right panes, the scroll view also needs to be scrolled if the selected time is not included in the currently selected time range.

[farismhmd1]

Hi,
I used pod file in my project. but these changes are not there in the latest version. why these changes are not in the master?

[HHK1]

Because the implementation is not complete, and merging this to master would result in bug tickets. I'd rather have a missing feature, than a buggy one. If you want this feature, please consider opening a PR :)