1.11 Minor fixes

1.11 Minor fixes

• Change the way a marked area is highlighted from reverse to a different background color. That works well for black chars on yellow background (code 43). For white chars on black background, the setting for background color in the function hilite() has to be changed, e.g. to blue (code 44).
• Save file to a temporary file first, and rename it to the target name after successful write.
• Lazy screen update: defer screen update, until all chars from the keyboard are processed. Not available for WiPy