Update Finnish translation for 5.4

Also fix minor mistake in string "Files of type:".

Consistency checks (source -> translation):
* socket -> pistoke
* escape sequence -> ohjauskoodi
* (XML) tag -> tunniste
* XML declaration -> XML-esittely

Change-Id: Ia530f8bb0badea488afc7fb45dc62100b4f1dd96
Reviewed-by: Aki Koskinen <qt@akikoskinen.info>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Catalan translations updated for 5.4

Change-Id: I71eae55086b23c56918e6fe4d7faa1104ff09236
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Added Latvian translations for qtbase, qtdeclarative and qtscript

Change-Id: Ic5b3c9dff74281e78d43c2d29dc8f9510a7deb8d
Reviewed-by: Ingmārs Dīriņš <melhiors14@gmail.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>