Add configurable Tab Out support

Add an optional Tab Out behavior that moves a single cursor past configured trailing characters when pressing Tab. Expose the feature in Global Document Settings, keep it disabled by default, persist its configuration, and preserve existing selection and multi-cursor indentation behavior (SpartanJ/ecode#951).

src/tools/ecode/settingsactions.hpp

@@ -25,6 +25,8 @@ class SettingsActions {
 
 	void setIndentTabCharacter();
 
+	void setTabOutChars();
+
 	void setFoldRefreshFreq();
 
 	void setUIScaleFactor();