added sections account and webkey info, moved contact section to user manual, other small changes

1. added Motivation and URL as sections in chapter 1

2. moved 'Contact' section to User Manual chapter

3. created 'Contact' section in chapter 1 with reference to relocated section in User Manual chapter

4. added 'URL' and 'Account' sections in User Manual chapter with subsections for
description of registration process and explanation of webkey plus webkey generation

various other minor changes