Add new function ShadowLoad

key: able to write out shadows

key: add shadow keys

Add (*Section).NewBooleanKey method

Fixes go-ini#87

Add error check for PR go-ini#77

Detect reflect.Float32 in setWithProperType

Fixes go-ini#86

Support for loading from io.ReadCloser

Closes go-ini#79

Minor fix and docs for PR go-ini#72

Bump version

go-ini#53 support boolean type key