Corrects bug 476: PyToggleTargetAdapter is registered too broadly.

Changes the adaptabletype from org.eclipse.ui.texteditor.ITextEditor
to org.python.pydev.shared_ui.editor.BaseEditor.

Change-Id: Ib4e81f9f2cfe08510528d64e11498a3d28ab2e25
Merge pull request #132 from dannyyoo/bug-476

Corrects bug 476: PyToggleTargetAdapter is registered too broadly.