Version 2.0.0, with breaking changes.

- Changed error handling -- VCL failure for unrecoverable errors,
  see the ERRORS section in the manual (README). This is a breaking
  change.
- set .compile() is unnecessary and deprecated, but legal for the
  time being.
- Add set .subroutine() and .check_call()
- Requires VRT 13.0, compatible with Varnish 6.6

version 1.11.0, compatible with VRT 13 (Varnish 6.6)

version 1.10.0, compatible with Varnish 6.5

Version 1.8.0, compatible with Varnish 6.3.

Version 1.5.3, adds integers associated with set elements, and backports various methods and functions

v1.6.1-2, adds integers associated with set elements for Varnish 6.1

v1.7.0, adds integers associated with set elements for Varnish 6.2

v1.6.2 compatible with Varnish 6.2.0 / VRT 9.0

version 1.6.1, packages for VRT 8 (Varnish 6.1 & libvarnishapi.so.2)

version 1.5.2, packages strictly for Varnish 6.0.x

Version 1.6.0, RPM builds for VRT 8.0 / Varnish 6.1.0

Version 1.5.1, compatible with Varnish 6.0.1 and 6.1.0

version 1.4.5, backports the bugfix for off-by-one error for rewrites for compatibility with Varnish 5.2

version 1.5.0, bugfix off-by-one error for rewrites

version 1.4.4, compatible with Varnish 6.0.0

version 1.4.3, enforces ABI compatibility with VRT 6.0

version 1.4.2, requires Varnish 5.2, suitable for RPM packaging

Version v1.4.1, backports set.which(), .string() and .commit() for Varnish 5.2

Version 1.4, compatible with Varnish 5.2 and RE2 since 2015-06-01

Version 1.3.1, compatible with Varnish 5.1.x and RE2 since 2015-06-01