Migrate from v5.x to 5.11+

Migrate SmartFormat.NET v2.7.3 to v3.2.1

Heads up

• Up to version 5.10.0 we had a package reference to SmartFormat.NET v2.7.3
• From version 5.11.0 we have a package reference to SmartFormat.NET v3.x

Version 5.11.0 is API and source compatible with prior 5.x versions.

But the new major version of SmartFormat.NET incurs breaking changes. MailMergeLib manages breaking API changes under the hood. Other breaking changes are related to using SmartFormat formatter extensions in placeholders:

1. If you're only using plain placeholders like "{Email}" or even "{Today:yyyy-MM-dd}" there's no need for updating the format strings, and you're fine.
2. If you're using formatters like "{Fruit:cond:Apple|Pie|Orange|Banana|No fruit}", where the rendered string depends on the Fruit variable, urgently have a look at https://github.com/axuno/SmartFormat/wiki/Migration#2-formatter-differences-from-v2-to-v3 .Required modifications are not extensive, but unavoidable.
3. On the other side SmartFormat v3 has many advantages:
   • Parsing is 10% faster with 50-80% less GC and memory allocation
   • Formatting is up to 40% faster with 50% less GC and memory allocation
   • Nullable notation inside placeholders
   • much more

See more details here: https://github.com/axuno/SmartFormat/wiki/Why-Migrate