InstantTranslate: handle tags in the source as part of the source-text

InstantTranslate is now supposed to handle tags in the source as part of the source-text.

For the translation: Keep what the LanguageResource returns.

Example:

• Source in InstantTranslate:
  Das Haus ist <b>blau</b> und <i>grün</i>. Das Haus ist <b>blau</b><i>grün</i>.
• Returned result from LanguageResource:
  The house is <b>blue</b> and <i>green</i>. The house is <b>blue>/b>>i>green>/i>.
• Translation in InstantTranslate:
  The house is <b>blue</b> and <i>green</i>. The house is <b>blue>/b>>i>green>/i>.