major refactor; added floating point arithmetic; added transparent (requires composit...

major refactor; added floating point arithmetic; added transparent (requires compositor) label as a new element; now 'wait' command can take millisecs (specified as fractions of seconds, ex.: 0.040); added raw draw operation command '/' with subcommands to draw line, points, polygons and arcs (for each element); added special variable reference operator '&' that works like '@', but gives error if the variable is empty; added more math functions; added rand and hex function; added 'line' attribute in style string to specify line width in pixels; added additional examples; removed join operator; fixed makefile; fixed join function; minor fixes; refactored tests.