Add more holidays to the Fi translation

Add some missing holidays to the finnish translation file. Also properly name and cleanup some old comments and holiday names.

js/language/fi-FI.js

@@ -105,14 +105,18 @@ window.calendar_languages['fi-FI'] = {
     //   - Easter and the day after Easter: 'easter>easter+1'
     //   Limitations: currently the multi-day holydays can't cross an year. So, for example, you can't specify a range as '30-12>01-01'; as a workaround you can specify two distinct holidays (for instance '30-12>31-12' and '01-01'). 
     holidays: {
-      // January 1
+      // January 1, 6
       '01-01': "Uudenvuodenpäivä",
-      'easter': "Pääsiäinen",
-      // May 1
+      '06-01': "Loppiainen",
+      'easter-2': "Pitkäperjantai",
+      'easter': "Pääsiäispäivä",
+      'easter+1': "2. pääsiäispäivä",
+      'easter+39': "Helatorstai",
+      'easter+49': "Helluntaipäivä",
       '01-05': "Vappu",
-      // December 6
       '06-12': "Itsenäisyyspäivä",
-      // December 25
-      '25-12':  "Joulupäivä"
+      '24-12': "Jouluaatto",
+      '25-12': "Joulupäivä",
+      '26-12': "Tapaninpäivä"
     }
 };