improves module function / code handling: trip_search.css and calendar.js

Please update your file trip_search.module

Change the code of the function trip_search_html_head().

New version:

function trip_search_html_head() {
  theme_add_style(drupal_get_path('module', 'trip_search') .'/trip_search.css');
  drupal_add_js(drupal_get_path('module', 'trip_search') .'/popupcalendar/calendar.js');
}

and create new file "trip_search.css", contained styles.