func (c *Changelog) GetVersion(versionNum string) *Version {
	for _, v := range c.Versions {
		if v.Version == versionNum {
			return v
		}
	}
	return nil
}
GetVersion fetches the Version struct which matches the versionNum.
Returns nil if no version was found matching the given versionNum.
package changelog
func NewVersion(versionNum string) *Version {
	return &Version{
		Version:     versionNum,
		History:     []*ChangeLine{},
		Subsections: []*Subsection{},
	}
}