WIP add control box under progress bar

The control box is created by the new controls module. It holds tab
toggles. Time controls are always visible.

Known Issues: The time control click handlers aren’t  attached properly
and thus do nothing. This commit is meant for styling only.
rewrite tab creation

Each tab is an instance of the new Tab-module. The share, downloads and
info tabs were rewritten to use it.
They are all added to the tab registry in each player.

Known Issues: The chapter tab is disabled until it is rewritten as well.
rewrite chapter tab

The chapter tab is an instance of the Tab-module as well. It is added
to the tab-registry.
Each chapter tab gets a reference to the update function to enable
highlighting of the currently played chapter.

TODO:  There is a need for a global update hook that can be listened to
by each tab.
Set config.rb to CSS output style with line-comments
Readme-update: Correct path to build podlove-webplayer.js
Rearrange markup for audio title area

- create wrapper for title and subtitle (h2 and h3)
- refactor calls for rendering the HTML for title area
- add some comments
Style title area with playbutton on the right

- pull playbutton .bigplay to the right with floating right
- add margin-right to subtitle to avoid covering the playbutton
rename class 'podlovewebplayer_controlbox' to 'tab'
update package.json
fix chapterTab name
refactor controls module

Controls constructor requires the player it is associated with as its
parameter.
Controls#createTimeControls requires an instance of the tab, the
chapterTab object.
Add getCombinedCallback utility function. It combines the standard
click handler with the specific given one.
add show property to configuration object of example players
disable line comments in built CSS by default

The current CSS output was added as well.
player module overhaul

Render show title with link to show main page when present.
Use playerType where applicable in main method.
Put all utility functions to the end of the module.
Adapt tab concept in title area and control area //card #43

- create and import tabs.scss
- increase base font from 13 to 16px for better readability
- remove link-color from headlines in title area
- this commit fixes rearrangement of header/title area in task https://trello.com/c/RvbGlFAl
add method getStartTimeCode to timecode module
timecode.parse always returns an array
Create header element for headlines and subtitle in title area
Restructure Title Area & Refactor SCSS

- Create & import partials for layout elements 'controlbox' and 'titlebar'
- Delete obsolete browser prefixes in titlebar elements
- Positioning fixes for elements in titlebar
Add class 'flexer' to Titlebar for flexbox layout