Improve user-friendliness

[nam32]

1. Description of options clearness could be improved (e.g. "Get lines by country and year" what are lines?).
2. Mistyping can result in users being returned to the main page and users must navigate back to the second menu from the main menu again e.g. typing cities name into "Get lines by country and year" results in users being returned to main menu with no error messages) while mistyping in other options can result in users being stuck in a loop (Get maximum values for countries and time period option)
3. Exact terms must be searched in order to yield results (e.g. country names - errors and suggestions are not returned to help users.