Refactor AUI to new code style convension

1. Use `value()` getters instead of `getValue()` - does the same job but shorter.
2. In Doxygen documentation, use `@` instead of `\` because `@` is more common.

Start by inventorying the AUI codebase for getValue() getters and backslash-style Doxygen commands. The work is done when the requested getter and Doxygen conventions are applied consistently across the project; the issue names no specific files or tests.

Written by the indexing model from the issue text.