Correct implicit conversions in Number.
Correct implicit conversions in Number.

Thanks to ellchow for spotting this one.

Fixes #40

siddhartha-gadgil/spire,AlecZorab/spire,non/spire,rklaehn/spire,JackSullivan/spire,codeaudit/spire,guersam/spire,kevinmeredith/spire,non/spire,guersam/spire,siddhartha-gadgil/spire,adampingel/spire,woparry/spire,adampingel/spire,codeaudit/spire,kevinmeredith/spire,JackSullivan/spire,tixxit/spire,woparry/spire,AlecZorab/spire,tixxit/spire,rklaehn/spire