Fix default Ice version for Ubuntu
Create installing from source chapter and split Using Git section

Move Git page to checkout the code and build system to the new chapter
Add references to the Linux & OS X waltkthroughs
Fix links to source code page
Fix introductory paragraph of Installing OMERO from source chapter
Update OSX configuration used to test the Homebrew installation
Add reference to dev doc in the walkthroughs Development server section
Add recommended shebang line to conf.py
Fix order of Debian from newest to oldest
Add link to source code page in Using Git and fix GitHub spelling
Allow to build documentation offline
Edits to XML, schema & specifications sections
merge dev_4_4 -D org -I include -E exclude: PR 281 (Review Matlab documentation (see #10389))
merge dev_4_4 -D org -I include -E exclude: PR 291 (Add "Link" action to permissions table and to the Key 4)
merge dev_4_4 -D org -I include -E exclude: PR 296 (Putting OME-XML formats docs into ome-docs repo)
merge dev_4_4 -D org -I include -E exclude: PR 301 (Walkthrough fixes)
merge dev_4_4 -D org -I include -E exclude: PR 303 (Add recommended shebang line to conf.py)
merge dev_4_4 -D org -I include -E exclude: PR 304 (Allow to build documentation offline)