FE: Quick filters, include text filter

[manusa]

Requirements

• Quick filter dialog includes Textfield to allow quick filtering of messages by introduced text
• All text matching is performed ignoring case and unicode characters (À -> A, Ë -> E...)
• If textfield includes text, messages are filtered according to (OR):
  • Subject contains text
  • At least one from contains text
  • At least one recipient contains address with text
• Selected option / filters are cleared whenever a folder is selected (even if it's the same folder)

##Relates to:

• #210
• #218

[manusa]