Merge pull request #258 from Piscean/master

Fix for 219, do not remove white space
Changed how Task.cs captures projects and contexts to ensure that duplicate values are only counted once.
Added task list metadata properties Projects, Contexts, and Priorities to TaskList.cs.
Changed source of projects and contexts for Intellisense method to newly implemented TaskList properties Projects and Contexts, to marginally improve performance.
Added PrimaryProject and PrimaryContext properties to Task.cs, and use them in the MainWindowViewModel.cs sort routine to return task list sorting behavior to how it was in version 3.1.0. Sorting will be done by the first project or context written within the task raw text.
Added IntellisenseTextBox class, to extend Intellisense behavior to any textbox in the application, notably to the Filter window. Addresses Issue #66. IntellisenseTextBox not used yet in this commit.
Implements IntellisenseTextBox in MainWindow.xaml. Related to Issue #66.
Implements IntellisenseTextBox in FilterDialog.xaml. Closes Issue #66.
Fixes a bug in IntellisenseTextBox.cs that occurred when the Intellisense list is empty and the user selects a null Intellisense list entry for insertion (with Enter, for example). Addresses Issues #66.
Merge conflict; general tidying
Merge pull request #1 from benrhughes/dev

Pull from benrhughes:dev