Add completion modules

[pbogut]

• Add completion for template files
  • In template="" attributes.
  • In attributes with xsi:type="string" and name="template"
• Add completion for events:
  • In <event name=""> attribute, event list is static, so only Magento events (no custom extentions).
• Add completion for PHP Classes
  • In <preference for="">, <preference type="">
  • In class and instance attributes.
  • In tags with xsi:type="object" attributes.
  • In <backend_model/>, <frontend_model/> and <source_model/> tags.
• Add component completion in xml and js files
  • In tags with name="component" and "xsi:type="string".
  • In argument list for define() function in JS files