Remaining nitpicks from Mark & JM

Conflicts:
	developers/Clients/ImportLibrary.txt
	developers/Model.txt
Fixing links I broke
Fixing ImportLibrary as per Josh's suggestion
Final nitpicks from Mark
And the ones I missed!
VistorPatter to VistorPattern
Begin improving DSL section

Based on the notes I took while discussing
the build and the server code in Dundee.

 * Add model-generation.png from the Nature paper
 * Merged TypeLanguage into Model
 * Added specifics comments about generated files

Conflicts:
	developers/Model.txt
	developers/Server/ExtendingOmero.txt
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 256 (Developer doc tidy 3 rebased)