v0.15

Version 0.15.

Changes:

• Issue #26: fix Nonetype error while parsing temperatures
• Update README.md
• Z-offset fixes for S3D and Prusa Slic3r
• Moar fix for S3D temperature handling
• Fix temperature setpoint detection
• Add support for Prusa Slic3r 1.37.2
• Issue #18: print raft just before infill/purge
• More fixes after refactoring
• Fix Delta tower position regression
• Update gitignore
• Issue #16: move Z close before printing raft
• Issue #19: fix tower not generating fully
• Add raft extrusion multiplier GUI control
• Raft speed to use slicer defined speed
• Refactoring: settings-module