Load and write project settings

[jakimowb]

Allow to save and reload EOTSV settings from QGS Project files:

• Time Series
  • Time Series Source + source visibility (source is visible/not)
  • Time Series Date (TSD) visibility (date is visible/not)
  • TSD precission (year, month, week, day, hour, minute, second)
• Map Widget:
  • Map Size
  • Number of Maps per Map View
  • current date
• Map Views:
  • name, visibility
  • Layer-Tree
    • time-series sources: sensor-specific visibility
    • none-time-series sources: name, style
    • layer-order, including layer groups
• Docks & Panels
  • visibility
  • size
  • location in QMainWindow
• Main Window:
  • size (max by given screen size)