Name search and operator escape in `filter()`, new `select` directive, merge operator `~`

What's Changed

• Add a Toolbelt Catalog entry for fmf by @psss in #216
• Limit number of tests run for integration with tmt by @lukaszachy in #225
• Turn schema validation method into a stand-alone function by @happz in #189
• Small cleanups by @LecrisUT in #237
• Allow filtering based on the node name by @psss in #219
• Add directive select to force selecting node by @lukaszachy in #223
• Avoid copy() calls in adjust() by @lukaszachy in #229
• Accept additional rules in the adjust() call by @lukaszachy in #230
• Support escaping | and & in utils.filter() by @psss in #220
• Implement the ~ merge operation by @lukaszachy in #234
• Extend the filter() documentation slightly by @The-Mule in #235
• Introduce a new page for release notes by @psss in #242
• Release fmf-1.4.0 by @psss in #243

New Contributors

• @LecrisUT made their first contribution in #237
• @The-Mule made their first contribution in #235

Full Changelog: 1.3.0...1.4.0