Unexpected removal of indentation when hitting enter

[pskowronek]

Description Unexpected removal of indentation when hitting enter

Steps to Reproduce

1. run RSyntaxTextArea Demo Application - gradlew run
2. add the following text:
3. hit enter on 5th line

4. 

Expected behavior The indentation should be kept on 6th line (at least this is a behavior observed in other editors)

Actual behavior Indentation is lost on 6th line

Screenshots See steps to reproduce

Additional context Originally reported in https://github.com/mucommander/mucommander/issues/878