Fixes mnemonic accelerator key conflict of "Tracking" and "Start Tracking" in today.ui

Created by: ghost

Switched the underscore shortcut character of "Start Tracking" from "T" to "S", this no longer conflicts with "Tracking" and allows quick keyboard-only usage of Hamster.

Please check some of the translation files as I think my editor may have re-encoded them, causing them to completely replace one another with git.

Have also fixed a translation error in nl.po

This resolves issue #213 (closed)