Safe inputs and crashes

[maxscheurer]

User inputs are not checked for validity at the moment.

[maxscheurer]

List of problems:

Crashes 🔥

• clicking on Statistics when no data is loaded
• creating TCL script when no data is loaded
• Cancelling "Export session" (if no data loaded?)
  if self.contacts is not None and self.analysis is not None: AttributeError: 'MainWindow' object has no attribute 'analysis'
• Cancelling "Import session"
  line 165: importDict = pickle.load(open(importfile, "rb")) should not be called
• Sasa calculate button check input

Inputs 💻

• check for numbers in Analyze/Input text fields (sometimes QValidator is good to use)