Removed getParagraphElement from OdtDocument

This function only redirected to the OdfUtils version and many callers
already had an existing instance of OdfUtils to use. Any callers who did
not have an instance of OdfUtils now create one to continue using the
function.
Remove style element functions from OdtDocument

Removed getStyleElement, getParagraphStyleElement and
getParagraphStyleAttributes from OdtDocument as these functions simply
redirect to their implementations in odf.Formatting.
Merge pull request #777 from satsuper/interface-cleanup

OdtDocument interface cleanup
Provide hook to prevent alerts from being shown when logging
Make browser assertions throw a proper Error type instead of a string

Error objects can have stack traces and other things to make diagnosing
asserts easier.
Remove unused 3rd parameter of runtime.assert

This 3rd callback parameter is never used inside the current WebODF
source.
Standardize all runtime assert implementations
Merge pull request #731 from peitschie/disable-alert

Provide hook to prevent browser alerts from being shown when logging
Fix crash if a split paragraph occurs with no text elements selected
Use text style from the selection start when splitting a paragraph
Merge pull request #776 from peitschie/p-style-crashfix

Fix crash if a split paragraph occurs with no text elements selected
Fix mimetypes for .ods & .odp files in nodejs httpserver
Add ODF template variants to mimetypes set by nodejs httpserver
Load ODFViewerPlugin also for all template and flat variants of odt/odp/ods
Extend OdfContainer.DocumentType with template versions
Make template-type-state of document setable and queryable
Expose setTemplate/isTemplate in Wodo.TextEditor API
Note added support for document template variants
Support template types in docnosis
Make Wodo demo/testing code properly handle template documents