#80 Sequence Font declared in multiple places

[Steven Blanchard]

IGB's graphics compute the width of characters from the static final Font NeoMap.font_for_max_zoom. The font actually used for partial sequences is hard coded in CharSeqGlyph.mono_default_font. Searching the code for "Courier" and "Monospaced" brings up a number of hard-coded font references used in character sequences. They should all reference the same variable or constant, as only one font can be used at a time when displaying sequences on Maps since the character widths need to match.