set_blanket: remove geom_linewidth and geom_size

[davidhodge931]

Likewise in weave_geom_aes and weave_annotate_aes

Why:

• Need different sizes/linewidths required for different geoms
• Often just as easy to use update_geom_defaults("line"= aes(linewidth = 1)) etc

set_blanket(geom_colour, annotate_colour)

Also consider changing default linewidths for line type geoms to 1