Currently, the HTML escaping is controlled with two modifiers: **e:** and **u:** and the programmer may replace the default handler. There must be a system that allows to define more modifiers and assign the handlers for them. The areas that must be modified:

- Ability to choose the modifier for XML attributes.
- Ability to choose the default global modifier.
- Ability to choose the per-template modifier (changed the behaviour of "escaping" attribute).
- Ability to choose the per-expression modifier.
- The snippets remember the modifier they have been created with.

Expected behaviour:

* Each expression must use exactly one modifier (the "no-modifier" variant will be implemented as a fake modifier).
* If there are two candidates for the modifier, there will be used the one with the highest priority (per-expression, per-template, global).

A note about the template syntax. As we are going to use the ":" symbol to specify the expression type, too, there must be provided a hierarchy:

1. The modifiers use one-letter symbols.
2. The names of the expression engines must be at least two symbol long.