Check the clicked mouse button before dragging

added boolean to destroy method to optionally preserve sizes

throw an exception when the element matching to a selector was not found

Update README.md

Created a table of contents.

Activating Open Collective

Resizing stalls if the mouse leaves the container

Add ability to access parent and pairs

Added the ability to see the parent and the pairs associated with a particular split widget.

add the typescript definition

replace yarn install with yarn add

fix typo

fix json spec