Use 4 position version

[sreed4]

We use 4 position versions, as in V2.1.3.4, which represents major.minor.feature.bug. I would like to see an option that allows setting which position should be changed. For example, in .versionize

{
  "versioning":  {
    "positions": [
      {
        "type": "feat",
        "position": 3
      },
      {
       "type": "fix",
       "position": 4
      }, 
      {
        "type": "release",
        "position": 1
      },
      {
        "type": "update",
        "position": 2
      }
    ]
  }
}