fix(handler): do nothing if element array is empty

This is here to prevent bug, when multitouch object were losing focus,
and we were dragging body or html tags. When this happens, client sends
us drag event with empty element array.
fix(handler): fix corner calculation

Previously we considered that wams library was sending touch point, now
we consider that wams is sending offset of the element.
feat(element): provide relative offset of element

Before we were sending absolute position of element on the whole
workspace, now we are sending position of element relative to client's
screen.
feat(touchPoint): do not save touch point in element

Save touch point for element in memory.
fix(touchPoint): do not fix touch point on remote events
feat(moveElement): provide offset instead of touchpoint

Previously we were providing touchpoint to move method, now we provide
offset of the element that we want to move.
In other words, previously we were moving touchpoint of element, now
we move (0, 0) point of element.
feat(remoteMTEvents): inject source of data as in wams library
feat(app): provide handler on touch and release events
chore(sharedWorkspace): forgot semicolon