Fix crashes when double-clicking folder in tree

Editor was throwing an exception whenever you double-clicked a folder
node to expand it as it was attempting to load the folder as a file
Fix TaskList crash, update build for plugins

TaskList plugin no longer crashes on load if no project is loaded;
updated editor project references so the most recently-built plugins are
always used
Merge pull request #5 from powercommand/master

TaskList and ProjectTree hotfixes + plugin build updates