Selection Management step 1

[JiuqingSong]

I was planning to start the PR once I finished all steps, but it turns out that I still need some more time to finialize the other steps, and the first step can already fix the "paste hyperlink cause cursor pos wrong" issue, so let's start the first step PR.

The general idea of selection management is to cache a selection range every time a selection has been changed. In the first step, I split the core API select() into two steps:

1. create selection range from several combinations of parameters (this part is merged to existing API createRange()):
   1.1 Single node => range around the node
   1.2 Two nodes => range around the two nodes
   1.3 Node+offset => collapsed range at the node+offset
   1.4 Node1+offset1+node2+offset2 => range start at node1+offset1, end at node2+offset2
   1.5 Node+startPath (number[]) + endPath (number[]) => range start at start path, end at end path
   1.6 Single NodePosition => collapsed range at the position
   1.7 Two NodePositions => range start at position 1, end at position 2
2. select the range
   2.1 Rename the API to selectRange
   2.2 Add a parameter ''skipSameRange", when set to true, do nothing if new range is the same with existing one
   2.3 deprecate the old API select()

Then change the core API focus() to use selectRange() API with skipSameRange=true, to avoid lose current format state (B/I/U) when call focus().
Change all places where select() is called to new API.
The name and parameter list of Editor method Editor.select() are not changed,

[titrongt]

Is the IE exception that selection has no rangeCount? Curious what then is the behavior in IE?

[JiuqingSong]

It should be an IE bug.

[titrongt]

Is this a duplicate of the const defined in selectRange?

[JiuqingSong]

This is the public editor API, while selectRange is a CoreAPI and can't be called outside editor.

[titrongt]

If you always break out of the for loop once the conditional is not true, doesn't that mean you only ever check the index of 0? Why do you need a loop in this case?

[JiuqingSong]

This is existing code, moved from getSelectionPath.ts. It has been there for a while and run perfectly. So I believe we don't need to change it.