WordEmitter, DOCX: Improve current docx-output to simplify the created wpml-structure of docx

[speckyspooky]

The current word emitter has currently some challenges if the user tries to work with the result.
From user side the BIRT-docx isn't like a standrad word-document and it is not easy to change the word-documents based on the created huge count of grids and empty lines (paragraphs).

The main topics are:

• The emitter creates for each HTML-text-element a wrapped grid.
• Multiple specialized empty paragraphs will be used.
• Based on this systematic of used wmpl-grids the additional empty paragraphs are necessary to avoid exceptions if docx-document will be opend.
• The the header and the container area get a grid by default
• The list element get for (BIRT-)styling reason a grid (which is fine) but with additional empty paragraph

Discussions were done before:

#1352 DOCX with additional lines add header and footer

#1879 DOCX grid arround all HTML-wrapped text paragraphs

Reserach result:

• HTML-text grid-wrapped: The main reason is that the grid will be used for margin-padding implementation. And further investigations (debugging) shows that the main cause of the usage is the usage of the MHT-file for HTML-text and the wrong usage of supported HTML-style-attributes for MHT-HTML which can be converted/understand by Word.
  When the correct attributes will be used the margin is given like on my implementation of the Label-element.

• Header-Footer-grind: Is not longer necessary because it has no specific effect (comfirmation of Word emitter generates extra paragraph markers in footer and header #1352). Different style tests had no negative effect if the container wasn't added. The positiv effect was the structure is easier and the empty paragraph won't be added.

• List-element need the additional grid to implements the border effect. So it won't be changed but the empty paragraph isn't necessary.

Upcoming changes:

1. Improve the MHT-file handling to activate the standard margin
2. Allow the combination of margin & padding handling (point 1) to simulate the current handling
3. Avoid the additional grid and paragraph on header & footer
4. Avoid the empty paragraph of the list grid cell
5. Add new standard option for WordEmitter-user properties
6. All options can be controlled by user properties to change back the behavior because the docx-structure will be changed

Planned timeline:
I will implements these changes and will create a PR for BIRT 4.18

[speckyspooky]

This change is merged to the master with PR #1958