9292ov.nl: Use new `direction` property in journey details

Also, make departure/arrival platform translation more flexible by using
placeholders instead of string concatenation.
9292ov.nl: Great improvement of JSON parsing speed under Qt 4

Using QScriptEngine instead of Qt4Json under Qt 4 reduces JSON parsing
time by several dozen times.

See #121 - Slow parser performance
9292ov.nl: Additional slight improvement to parsing speed

Use value() instead of operator[]() to access QVariantMap members plus
use iterators to iterate over QVariantList.

See #121 - Slow parser performance
9292ov.nl: A bit of refactoring
EFA: Use new `direction` property in journey details