* feat: option to allow click on modalBackdrop to close modal
* feat: allow switcher modals closable
* feat: allow use caption field as modal title
* refactor: make maskClosable a variable
* fix: use "true"
* fix: code style
* docs: add description about maskClosable
* fix: convention is to have double quotes for strings in the TW core
* refactor: using a "mask-closable" field on the modal tiddlers instead of as a message parameter
* docs: move to modal tid
* Update WidgetMessage_ tm-modal.tid
* Make modals display in source Window
this makes modals display within the window where they got opened, with the parameter `rootwindow` that, if `yes` or `true`, shows the modal always in the root TW window (`<$action-sendmessage $message="tm-modal" $param="mymodal" rootwindow="yes|true"/>`)
* pass the full event to $tw.modal.display
we need the event there to find `srcDocument` and `srcWindow`
* pass event in options object
* update modal.js to use options.event
* add docs for rootwindow tm-modal attribute
