Added file dialog to choose contact profile images when clicking on the image well. Profile images are now cropped and scaled to the standard size when added to a contact. Refactored code for adding custom labels (previous workaround no longer needed). Added validity checks for new/edited contact details (must have non-empty name or company). Added handling of company contacts (i.e., those with a company name but no personal name). Refactored some of the OAuth and Crypto code (variable casting and general cleanup).