Escaping of expressions (statements) is now done automatically if not controlled by the user

Code review status [in progress; Jakub]

- [x] f20b2e06d7eac607074bffbc0c0b86433f016e33
- [x] 9c221b865b78b52cd3a32f75b140ee6b56f1bb6c
- [x] ec2a1baa13364ef4d05ba9f95eaa5e2a3e8aada0
- [x] 142bebbfd41bef25963d9d3d22a48b03961322ea
- [x] a301e7b42e8d7204394a4e2fd56eec347a640915

----
## Code improvement

Implementing the feature didn't require a lot of code change (basically just removing the code keeping the backward compatible mode). However, the code required some cleaning. The comments/JSDoc as well have been improved.

- implementation of the feature (in the Statements class)
- implementation and tests for the modifier implementation: notably adding the documentation for the "arg" argument (corresponding to the "options" argument of the String utility, see next point)
- implementation and tests for the related String utility implementation: notably it's easier now to understand how the "options" argument works

## Internal code update regarding the change

Expression intentionally outputting HTML have been identified and changed to disable the automatic escaping.

Concerned pieces of code are:

- some tests
- some widgets' templates
- the tester application
- the debug tools (contextual menu)

## Unrelated fixes

- the aria.utils.Bridge class can now actually load the development files of the framework (used for the debug tools).
- in JSDoc comments: some parameters were documented with the @param[in] syntax, which is not understood by the JSDoc parser we use, so I removed this syntax in favor of the usual one @paramhe usual one @param