rng: avoid recomputing a constant every time
color: add serialize/deserialize
all: drop some workarounds that are not needed anymore
make stuff into command line options
add README and an example
build the final scene from the first book
initialize random generator in main
flip the image upside down
control number of samples with a global constant
make camera relocatable and relocate it
imperfect metal reflectance
implement lambertian and metal material
increase t cutoff a bit
an amazing performance gain