GetInt(), GetLong() are exactly the same as GetValue() except that
their result is rounded and converted to the repsective data type.
Thus avoid code duplication and use GetValue().
The previous values do not influence the return value of the function
nor does looping over them have any side effect.
The next_repeats value is not used in any way, thus it doesn't need to
be calculated.
`Json::Reader` has been deprecated for some time, so we replace it with
`Json::CharReader` generated by a `Json::CharReaderBuilder`, or (in the
one instance where we have a stream as input) `Json::parseFromStream();`
Remove else so that the default return value is used if no other return was used."else if" in line 334 had no else and therefore in some cases no return value was present.
* Refactor of Coorindate and Keyframe optimized for performance (much faster than previously). Also refactored FrameMapper to not use a Keyframe, and to only process frame mapping when needed... speeding up Json loading of project files.
* Fixing FrameMapper linear calculation to match existing Keyframe calculation
* Fixing Keyframe to pass original unit tests, and correctly calculate the Keyframe repeat fractions and deltas.
* Small refactor of time mapped logic in Clip.cpp
