Add some improvements for wizards

Interface and header file wizards generate and add comments to files they
create if user chooses such option. Moreover, the header wizard automatically
appends '.h' extension to the entered file name if it is not present.
Add the component wizard and some improvements

The component wizard with all necessary fields and an icon is added. Moreover,
checking the correctness of an identifier is moved to a separate class
('pl.edu.mimuw.nesc.plugin.wizards.fields.IdentifierValidator'). All field
classes support enabling or disabling their controls. Furthermore, objects of
field classes that are derived from 'AbstractField' can be aligned - controls
after the label of the field will start at the same offset after the alignment
operation.