Selection scope: using context of **last** element used for selection initialization [Bugfix]

Using `window` and `document` globals, from context of last element. Workaround for problems with iframe.
Ignoring pointer while outside of document [Bugfix]
Release 0.1.2
EPUB-132: Removed jumping of marker while moving it down [Bugfix]
EPUB-132: Removed blinking of selection, while marker is being moved across paragraphs [Bugfix]
EPUB-132: Selection works again on Galaxy Note 10.1 [Bugfix]

Absolutely strange behaviour - We cannot select text (also with native selection) on webpage displayed in StageWebView on Samsung Galaxy Note 10.1 if html document contains canvas or any fixed (`position: fixed`) element.
Merge branch 'EPUB-132' into EPUB-128
Merged in EPUB-132 (pull request #1)

Removed jumping of marker while it's being moved
EPUB-128: Searching for closest letter on the left of pointer while marker is being moved.
EPUB-128: removed debugging call.
EPUB-128: Improved debugging tools.
EPUB-128: Improved searching for letter on the left of pointer.

Now, searching works also when we move maker on the right of paragraph. A multiline text node can be split to put marker in accurate position.
EPUB-128: Improved searching for letter on the left of pointer - Refactor stage 1
EPUB-128: Improved searching for letter on the left of pointer - Refactor stage 2
EPUB-128: Improved searching for letter near the pointer - Refactor stage 3
EPUB-128: Improved searching for the letter above the pointer.
Corrected demo title
Merged in EPUB-128 (pull request #2)

Searching for the nearest letter on the left of the pointer
Merge branch 'develop'
Release 0.1.3