Checked out UI changes from master
Enabled GridBagLayout, disabled column reordering
Added preview pane to render selected content into BibTeX
Refactored formatting a bit
Added comments
Added (ugly) filtering and preview panes
Minor UI improvements, couple of bugfixes
Autofill cite type when adding a row + cite key generation and focusing author field, lacks checks
Incorporated from master: removing all selected rows at once, not one-by-one
Merged ui-improvements with legacy ConvertTable