Pass over ==initializeWidgets==

- Adds more details about the purpose of this method
- Adds a pattern
- Adds an example
- Adds a section about instantiating sub wigdets

--------

Also adds a bit of details about the other pillars
Merge branch 'master' into heart_of_spec
Generate Markdown output
Update the titles
Generate Markdown output
Continue to fill up sections

- Changes the section label
- Adds a new definition
- Reformat the definitions
- Adds a note specifying if the method is mandatory or optional
- Adds info about `initializePresenter`
- Adds a section about the pragmas in specs
- Start to write examples about layouts
Change a tab in two spaces
More examples
Merge branch 'master' into heart_of_spec

Conflicts:
	book.md
Generate Markdown output
Finish with examples
Merge branch 'master' into heart_of_spec
Merge pull request #10 from SpecForPharo/heart_of_spec

Heart of spec