Add ask_folder dialog routine
Add the Chrome Core font Cousine Regular to our distribute fonts
Eliminate needless file operations when called from preferences
Multiple changes related to preferences: 1) add list_of_good_families() for loading
the preferences combobox; 2) Eliminate the choose_font full font dialog, not needed;
3) Eliminate the set_general() method, we are not offering a preference for the UI font.
Make docname modified color fixed, not making it a preference
Simplify and recode the colors handling to work with preferences Apply button.
Also eliminate the issue that when no find-range is set, a scrap of its highlighting remained.
Integrate the Preferences dialog.