Merge pull request #30 from magnusjerre/chapter9_doc

first draft of documentation
prestudy: First draft of revision
prestudy: Edited the today's solution part
prestudy: Initial rewrite of use cases
prestudy: almost finished
prestudy: Created a new usecase picture, updated the usecases
Added all chapters to main file again. Updated the figure references in lifecycle
Merge pull request #31 from magnusjerre/prestudy_revision

Prestudy revision
added the iterations
Merge pull request #32 from magnusjerre/iterations

added the iterations
Made some small changes to the prestudy
Finished both the prestudy and the estimation chapter
mostly spelling and latex updates