[sailfish] Made the content teaser optional

Closes #101 on sailfish
[sailfish] Renamed setting teaseContent to showExcerpt

Following the tt-rss naming.  Regards #101
[sailfish] Reorganized Settings Dialog

- Grouping according to pages
- Unify naming (from the users' pov; the variable naming is still a
  bit chaotic)
Ordered settings.hh and settings.cpp
[sailfish] Switched from ComboBoxList to ComboBox in Settings

Removed unused code from ComboBoxList, too.
Fixed return type
[sailfish] Let the user define the length of title & excerpt

Closes #102 on sailfish
[sailfish] Use SectionHeader instead of Label
Merge pull request #109 from michael-k/settings

Settings
[sailfish] Fixed overlapping of Label with Bubble

The width was 3*Theme.paddingMedium (or 2*Theme.paddingMedium without
an icon) to big.  Correct calculation:

width: parent.width - anchors.margins
  - (icon.visible ? (icon.width + icon.anchors.margins) : 0)
  - bubble.width - bubble.anchors.margins
  - Theme.paddingMedium

Details:
• anchors.margins
  Padding to anchors.left of Label

• icon.anchors.margins
  Padding between Icon and ListItem

• bubble.anchors.margins
  Padding between Bubble and ListItem

• Theme.paddingMedium
  Padding between Label and Bubble

This commit simplifies the code.
[Refactoring] Javascript: whitepaces + indentation + if-else
[Refactoring] Javascript: if-else
Removed unreachable code
Annotated private functions
Moved processPendingRequests() to EOF
Renamed proxy

The naming now reflects, that the proxy is only being used for images.
[sailfish] Fixed typo

Is  everywhere else.
[Refactoring] JS code style
Removed unused code
Removed unused `requestsPending['token']`