Remove unused compat files

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #1085
| Refs tickets  | na
| License       | MIT
| Doc PR        | na

The compat/api files are not actually included at all in the codebase so therefor can be safely removed.
Removed support for old smarty delimiters.