Changed Interval to @interval in tests
Changed a couple of @interval back
Exported @interval
Separated tests into 3 files and included them in runtests.jl
Split tests into 3 files
@interval macro can now take one or two arguments
@interval now works with variables
Removed a @show
Put back the number of bits of precision in show for Interval
Rewrote sin, cos and tan using @round. Still needs testing.