Drop Julia 0.5 support

v0.2.0

Avoid redundant call to max_exp10(T) (#18)

Input limits

Various fixes and improvements:

• More accurate handling of truncating floating-point values into FixedDecimal
• Parsing strings into FixedDecimal
• Lots of tests near limits of FixedDecimals

v0.0.1

Update CI URLs to point to new caching infrastructure