Add some tests to new wrapping image
TOC Depth filter function added

Add options to TOC to only show selected depth of titles ; ie pass 1,3
arguments to only show titles depth 1 to titles depth 3
Plus now you can have two+ TOC on your document, each different
#160 Refactor folders: Element, Container, and Exception
- Rename folder Section to Element
- Rename folder Exceptions to Exception
- Move Section, Header, Footer, Settings to Container folder
- Move Element\Footer\PreserveText to Element\PreserveText
Re-indent with spaces TOC Depth filter

Travis said spaces, not tab. Meh.
Container abstract class
Extends `Container` abstract class into `Footnote`, `TextRun`, and `Cell` element class.
Adding more functionalities to containers:
- Table: Ability to add footnote in table cell
- Footnote: Ability to add image in footnote
- ListItem: Ability to add list item in header/footer
- CheckBox: Ability to add checkbox in header/footer
- Link: Ability to add link in header/footer
Add unit tests for refactoring results
Add support for document headers and footers to Template class.
Load any number of headers and footers
Add element availability matrix and enable `addObject` in footnote and textrun
Remove HashTable and all related properties/methods. PHPWord doesn't (yet) need it.
Deprecate `createSection` in favor of `addSection`
Make one level Element folder structure (move Cell and Row up one level)
Merge #190, reorder methods (public, protected, private), and add example to Sample_07_TemplateCloneRow
Merge branch 'develop' into #160-element-container
Remove some duplication on Word2007 writers
Create new Element abstract class
Fix some test error
DocBlock and use fixes