Cpp: Update to match the FindIce macro behaviour

Additionally, include links to the upstream cmake documentation
and add common cmake search variables which might be required.
Initial content dump & TOC addition
Cpp: Capitalisation corrections
Merge pull request #947 from rleigh-dundee/cmake-ice2

Cpp: Update to match the FindIce macro behaviour
Initial reformatting
minor doc tweaks
minor adjustments to system configuration

includes,
* link to memory settings configuration
* removal of OpenGL clients (coming real soon)
explain more about the binary repository
Tidying, minor edits etc.
Installation: Specify what to do for N/A in package lists
Installation: homebrew mplayer provides mencoder
reorder lists of operating systems to promote Linux

suggested by @manics
reword sentence to remove active voice

suggested by @bpindelski
Adding bullet points to lists
Adding more links to version history
Merge pull request #948 from mtbc/server-config

improve and update server configuration documentation
Merge pull request #949 from hflynn/history

Adding OMERO version history to docs
installation: change 'is largely' to 'are mostly'
installation: Remove double spaces and reflow
Merge pull request #950 from rleigh-dundee/install-ice

Installation: Specify what to do for N/A in package lists