Updates #814

- Simplify the Sass a bit
- Put the button at the bottom
- Give it full width (plus some margin)
- Let the color match the chatbox type

updates #796

Fixes #796 New config option: `show_send_button`

* Adds show_send_button setting to docs

* Change log updated

* Improves send button CSS, style fixes and documentation corrections

* Adds missing setting in rendering template for headlines

* Translated using Weblate (Afrikaans)

Currently translated at 100.0% (267 of 267 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/af/

* Translated using Weblate (Dutch)

Currently translated at 36.3% (97 of 267 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/nl/

* Translated using Weblate (German)

Currently translated at 52.0% (139 of 267 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/de/

* Translated using Weblate (French)

Currently translated at 99.2% (265 of 267 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/fr/

https://greenkeeper.io/

https://greenkeeper.io/

Currently translated at 94.7% (253 of 267 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/it/

Currently translated at 52.4% (140 of 267 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/de/

Fixes #675 

* Made time format configurable

* Made changes to values of time_format

* Removed user restrictions on time format

* Added documentation for time-format config

* Edited changes.md

* Edited config doc

* Modified time-format explanation

* Added link to moment

* Added test to check rendered time

* Edited CHANGES and removeunncessary lines from time format checking spec

* Removed unncessary spaces

Currently translated at 100.0% (241 of 241 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/af/

Currently translated at 100.0% (241 of 241 strings)

Translation: Converse.js/Translations
Translate-URL: https://hosted.weblate.org/projects/conversejs/translations/af/

* Fixes the bug in displaying chat status during private chat(message carbons)

* Adds fix#628 to ChangeLog

* Changes Log added to version 3.0.1

* Makes the string alphanumeric

* Orders the logs with ticket number

Functions need to be bound.

- Document `optional_plugin_dependencies`
- Also make `converse-headlines` an optional dependency of `converse-dragresize`

updates #805

so that we don't confuse it with the case where it was manual.

Otherwise other plugins don't know whether the message was forwarded or not.