Started implementing a C version of treeview.
Implemented print_thread in c/tree.c
Implemented print_message in c/tree.c
Implemented print_line in c/tree.c
Added coloured output to c/tree.c
Remove deduplicated subjects from output in c/tree.c.
Imoved output of c/tree.
Improved graph drawing of c/tree.
Using unicode characters in c/tree.
Fixed bad character used when drawing graph in c/tree.