1.5.0

• sp_sph_harm has been removed for now as it's deprecated in scipy
• Number Types and Unit Systems are actual objects, rather than strings
• Additional input number type checks (e.g. positivity, integers) for operations that need them
• Raise a NumberTooBigException when trying to render a number that is too big for the maximum Number size/prec
• Fixed the number type of an operation never being decimal, even when the first parameter is decimal
• Fixed setting the number of decimal places before decimal point, correctly sets the total precision so we don't have more decimal places than total size