No default constructor

[Jan Jurzitza]

I want to store a SemVer version containing the current version of some program. It is defined at global scope because its how the API is designed. However it says the default constructor is disabled, so I cant compile. I tried initializing it with SemVer("0.0.0") but then it says it cant run the constructor at compile time because of regex.

Adding a SemVer.invalid static variable would also be useful.

[Dragos Carp]

Fixed in v0.3.0