choose session is not mandatory refs BT#7276
fixed indentation and coding style
Exercise progress report: deleted column 'correct'
choose session is not mandatory refs BT#7276
added correct column
Exercise progress report: hidden answer type filter
Reports, session is not mandatory refs BT#7276
fixed date format refs BT#7277
fixed code style
Exercise progress report, added exercise date filter
Survey Report, added date filter refs BT#7277