Implemented ICU4J

[bubblobill]

Identify the Bug or Feature request

progresses #5952

Description of the Change

Implemented ICU4J which allows the use of named parameters in message pattern strings.

This will improve the life of translators where parameters with useful names can provide context for the phrase.
Example:
Invalid condition in {0}({1}) roll option.
vs.
Invalid condition in {branchType}({condition}) roll option.

Added ParserExceptionBuilder class for easier construction of error messages using named parameters.

Additionally: Fixed issue with & replacement. & is now only removed if it is immediately followed by a alphanumeric character, and does not form part of a HTML entity. Strings like the following should render correctly:

States & Bars
Sights, Lights & Auras
Measures how opaque the "soft fog" overlay is drawn (0-255).

Possible Drawbacks

Having to create a map of name-value pairs can be tiresome. Thus the exception builder.

Documentation Notes

Implemented ICU4J

Release Notes

Improved context for future translation strings.

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This change is 

[kwvanderlinde]

I don't see where ICU4J is put to use. Looks like the named parameters work just as well without it. And the AbstractMessageFactory and implementations aren't used anywhere either. It's just the changes in I18N itself that seem to be doing anything.

[bubblobill]

@kwvanderlinde
Import changed from Java.text.MessageFormat. That's why it works with named values.

The message factory is a convenience tool. I'm not about to start writing new/rewriting translations without the change being adopted. Then you might see it used.

[kwvanderlinde]

@kwvanderlinde Import changed from Java.text.MessageFormat. That's why it works with named values.

See it now. Definitely off my game 😅

[kwvanderlinde]

I think the changes look pretty good. Just a couple nitpicks.

[kwvanderlinde]

@cwisniew Do you have any further thoughts on this one? I think it's good to go.

Requested changes have been implemented

[kwvanderlinde]

I'll take silence as implicit permission 😅 We can always revisit if needed.