Brief summary of issue / Description of requested feature:

Accidentally found our way to use tr("text", "comment") was actually quite outdated

Steps to reproduce the issue / Reasons for adding feature:

1. New recommended style: https://doc.qt.io/qt-5/i18n-source-translation.html#translator-comments
2. Current Mudlet style: https://doc.qt.io/qt-5/i18n-source-translation.html#disambiguation
3. In Qt 4.4 and earlier, this latter way was the preferred way to specify comments to translators. Nowadays it's only to be used to disambiguate otherwise identical strings

Error output / Expected result of feature

Switch all tr() to new style:

//: This name refers to a host name.
hostNameLabel->setText(tr("Name:"));

/*: This text refers to a C++ code example. */
QString example = tr("Example");

Extra information, such as Mudlet version, operating system and ideas for how to solve / implement: