Allow the auto-configurer to ignore unfit interpreters, and automate the folder selection step.

1) It is possible for the auto-configurer to find an interpreter that is incompatible with
PyDev before finding one that is compatible, thus causing the auto-interpreter to fail when
a usable interpreter is available. Change the auto-configurer to test every interpreter it
finds until one succeeds or until they all fail, rather than to select the first one it finds.

2) For the auto-interpreter only, automate the step where the user must select the folders
to be added to the SYSTEM pythonpath. The folders that are chosen are the same ones that come
pre-checked in the folder selection dialog for manual configuration.
Add a Preferences page for deciding whether a dialog should appear if no interpreter is set.

Instead of only being handled internally by PyDialogHelpers, disabling popups that appear when
the active project's interpreter isn't set up is now controlled by a Preferences page for
general interpreter settings, so that users can disable and re-enable the popups at any time.

In addition, make this new Preferences page the parent page of the Python/Jython/Iron Python
Interpreter Preference pages.
The default selection of interpreter PATH folders matches "Select All not in Workspace".

The folders that are automatically selected to be in the SYSTEM pythonpath when configuring
an interpreter are now the same folders that are chosen when clicking on the "Select All
not in Workspace" button in the list dialog. This is now also the selection of folders made
by the auto-configurer.

In addition, this patch renames some occurrences of "Iron Python" to "IronPython."
Add an "Advanced Auto-Config" option to interpreter configuration.

This config option searches for all valid interpreters automatically, but asks the user to
choose one of them (rather than automatically selecting the first one that works). The
folders to add to the SYSTEM pythonpath are also up to the user.

The old Auto-Config option has been renamed to "Quick Auto-Config".
Improve various aspects of interpreter auto-configuration.

1. Instead of searching for files that exactly match an expected name,
auto-configurers now search for files that begin with a certain string,
so as to allow discovery of different versions of interpreters (for
example, python2.7, python3)

2. Advanced Auto-Config now tests every interpreter it finds, and only
includes non-failing ones in the displayed list of interpreters to
choose from.

3. Except for in the Preferences Menu, configuration of an interpreter
(once it has been selected by an auto-configurer) is performed as a
user-level job, allowing it to be performed in the background.
Merged improved auto-configuration of interpreters.
Improved progress monitor update to deal with fast changes (as was the case in AsynchronousProgressMonitorDialog).
Merge branch 'development' of github.com:fabioz/Pydev into development