angle changes too much between characters it finds an alternate
placement), this is specified in the max_char_angle_delta property in
radians (feel free to change it to degrees).
It also improves the text placement around corners trying to minimise
the distance between the center of the character and the line on each
side. This is the major portion of the patch.
Map and Layer objects both have a new parameter 'srs', initialized to "+proj=latlong +datum=WGS84" by default.
Basic usage (Python):
p = Projection("+proj=merc +datum=WGS84")
point = p.forward(Coord(-2,51))
...
2.reflected arithmetic operators for Envelope/Coord into Python
3.altered return policies for python objects
4.modified build system to require proj4 lib and headers
