Sozi Release 19.04

This release introduces the following changes:

• Presenter mode HTML output (#211).
• Hierarchical frame list (#64)
• Editor: manual save/reload available in preferences (#442).
• Editor: fixed performance issue when reloading the SVG repeatedly (#424).
• Player: fixed visible scrollbar when the frame list does not fit the window height.
• Media: added an option to hide controls (#347).

Under the hood:

• Removed the dependency to bower.
• Based on Electron 3.0.2