Upgrade Notes

Major release! Upgraded underlying yaml parser, re-written majority of yq. This has brought on a number of features that have been in demand for a while (see below).

This is in beta and needs some community feedback and testing :)

# New Features
  - Keeps yaml comments and formatting, can specify yaml tags when updating. https://github.com/mikefarah/yq/issues/19, https://github.com/mikefarah/yq/issues/169, https://github.com/mikefarah/yq/issues/107, https://github.com/mikefarah/yq/issues/171, https://github.com/mikefarah/yq/issues/245, https://github.com/mikefarah/yq/issues/303,https://github.com/mikefarah/yq/issues/308,https://github.com/mikefarah/yq/issues/314
  - Handles anchors!  https://github.com/mikefarah/yq/issues/310, https://github.com/mikefarah/yq/issues/178
  - Can print out matching paths and values when splatting https://github.com/mikefarah/yq/issues/20
  - JSON output works for all commands! Yaml files with multiple documents are printed out as one JSON document per line. 
  - Deep splat (**) to match arbitrary paths


# Breaking changes

## Update scripts file format has changed to be more powerful. 
Comments can be added, and delete commands have been introduced.

Before:
```yaml
b.e[+].name: Mike Farah
```

After:
```yaml
- command: update 
  path: b.e[+].thing
  value:
    #great 
    things: frog # wow!
- command: delete
  path: b.d
```

https://github.com/mikefarah/yq/issues/305

## Reading and splatting, matching results are printed once per line.
  e.g:

```json
parent:
  childA: 
    no: matches here
  childB:
    there: matches
    hi: no match
    there2: also matches
```

```bash
yq r sample.yaml 'parent.*.there*'
```

old
```yaml
- null
- - matches
  - also matches
```

new
```yaml
matches
also matches
```

and you can print the matching paths:

yq r --printMode pv sample.yaml 'parent.*.there*'

```yaml
parent.childB.there: matches
parent.childB.there2: also matches
```