Added localization in multiple languages

During last week I added the support for localization. Now the user interface of Slide Four is available in English, German, French, Spanish and Italian.

In der Schule, Ich habe fünf jahre deutsche sprache gelernt, aber keine sprechen und sprachen, so... I forgot almost all ! This is very sad :-(

Later (spater?) during an University course, the teacher gave us a big book: The hardware specifications of Intel Pentium Processor, written in technical english, no italian translation available!! Initially i got crazy, but step by step I discovered that technical english is very simple.

Today, thanks to Google Translator, the localization process of Slide Four is much simplier. However, I think some mistakes remain, if you can find them, please email me the correct form.

Thank you..