Swift 5 and SPM

• A new tag format for release has been introduced to be compatible with Swift Package Manager(SPM). The new format does not include the v prefix in tag names. This will be the case for all tags going forward, previous v prefix tags remain in place and new tags without the v prefix has been pushed for these commits too.
• Added support for Swift Package Manager #296. Thanks to acecilia.
• Added support for Swift 5 #290. Thanks to jessemx109.