version 1.1.1

Announcing Fityk 1.1.1 -- new version of peak fitting software.

Changes:

• option exit_on_warning=0/1 was replaced with on_error=stop/exit; new option on_error=nothing allows to ignore errors in script.
• current working directory can be changed using new option cwd
• GUI: a new dialog for Model > Export Formula

• minor bug fixes