fix(scaling): pass rescale center when we pinch near limits

Previously we were only passing center when we were pinching normally.
Now when we very close to scale limits, we pass rescale center as well.
fix(scaling): fix mouse wheel scaling

Previously when scaling too fast, scale could become less than
MIN_SCALE or more than MAX_SCALE. This fixes this issue.
fix(scaling): mouse wheel scaling in firefox

Firefox does not support mousewheel event, but it supports
DOMMouseScroll event.
fix(pinch scaling): use setDiff to be more consistent