made it work and removed some unused code

the window to get events from the whole "window" in one place, and add
a reasonable sized border, which  can be coloured using resource files
or gtk_widget_modify_{b,f}g().

changed from char* to g_string for digits, should mean less alloc/frees

add functions to extract dna subsequences from main displayed sequence on coords or simple features or transcript features.

incorporation of column_spacing at either side of extreme columns

Have the scalebar on the left and text on the right (switching the text_left variable alters this)

This is not the best thing to do, but it's quick and if no-one likes it...