basic functionality working
fix generic_math link
added dim typeclass
before readding dimmed values
readded dimmed_value
renamed Power function
SI units with floats working
added scale to typeclass instances and added dimensionless unit
exp operator is now using floats (for rational powers)
rationals in power/2
added pretty-printer
added sum of dim
introduced si_unit_symbol(base_quantity) = string
split into libsi_units and test_si_units
ignore test executable
fixed dep on libsi_units
add test for sum of units
sums are probably working ^^
fixed spacing