HV-725 XXE formatting changes
HV-725 Adding listings from chapter 1 to source directory; Formatting
HV-725 Updating description of element types to be used for a constraint
HV-725 Adding listings from chapter 3 to source directory
HV-725 Making logging tip a section
HV-725 Fixing typo
HV-725 Trying to define structure. Creating a new (preliminary) group chapter and aligning chapter titles
HV-725 Updating po and pot translation files
HV-725 Working on groups chapter
HV-725 Changing chapter 3 to chapter 4 due to new group chatper
HV-725 Adding grouping examples to source tree. Some doc updates