Removing the non-IsIconic ShowWindow for the existing window at single-instance process spawn because it's unnecessary and has an unintended effect for automatic window arrangement

In the IsZoomed case ShowWindow has no negative effect, but is unnecessary

In the other window states (restored and arranged) ShowWindow SW_SHOW has a negative effect in the arranged state of changing the window state from arranged to restored
Copying SciTE's indentation detection and using the tab setting when indentation can't be detected (in an empty or indentation-less document).
Adding sql line comment.