Capitalize beginning of tooltips + Typos

Capitalized all remaining uncapitalized tooltips. 
+ Fixed typo in instantiate() function. Shouldn't have any repercussions on the code, AFAICT. 
+ other typos

src/Base/Sequencer.cpp

@@ -63,7 +63,7 @@ namespace Base {
 
     /**
      * The _instances member just stores the pointer of the
-     * all instanciated SequencerBase objects.
+     * all instantiated SequencerBase objects.
      */
     std::vector<SequencerBase*> SequencerP::_instances;
     SequencerLauncher* SequencerP::_topLauncher = 0;