Various updates to ease translators work.

Hi Woody

Access8Math is a very cool add-on. However, it is very difficult to translate, and not only because of the number of strings to translate or the math culture that the translator needs to have.

Here is a PR which intends to ease things for translators. I hope you are happy with it and will accept to merge it. If you want me to make some corrections, just let me know.

Here are the issues seen and fixed:

Issue 1: Case issue

In A8M, some controls (e.g. settings in dialogs, menu items) or messages do not start with an upppercase character. In usual UI, they do. So I have fixed controls in UI, as well as script descriptions. For translator, this allows to avoid PoEdit warning when the source text starts with lowercase but the translated text starts with uppercase.

Issue 2: Usage of "..." (triple dot)

In menu items, triple dot indicates that a dialog belonging to the same application will be opened. Triple dots are not used for menu items allowing to open a submenu. I have fixed where I have seen such issues.

Issue 3: Use of formatted string

Do not let translator re-translate again and again the same string. The about dialog information is always the same, only the version and the copyright year changes from a version to anoter. So I have made version and copyright year a parameter of the translatable string.

Issue 4: English

I have changed some formulation in English, which needed to be rephrased. However there are many places where a much better English phrasing would be helpful, especially for translators, but also probably for English-speaking users. I have not modified all the messages, because I am not a native English speaker, but I have just modified a subset of the translatable messages, especially those with grammar issues, since it really helps for translation, and probably also for native English speaking people. The grammar issue that I have fixed are mainly related to verb conjugation (present vs. past) and singular vs. plural.

For a further work, it would be very valuable to get help from someone speaking English natively and used to use math. More specifically, I have not modified the documentation (readme.md)

Issue 5: Translator comments

I have added a lot of translator comments and modified a few existing ones. I have tried to keep in mind that translator comments are not comments for developers reading or writing the code; but that they are targeting translators who have no idea of the context when looking at a .po file. Thus they do not need to explain the translatable string, but rather its context, i.e. where and how the translator can check his translation. For example:

"A setting in the rule settings dialog"
"A message reported when the user saves the file in the Editor" (these are just example)

Conclusion

All these changes are not exhaustive, e.g. there will still be English to correct or translator comments to add. But this is already a big part that should help translators.

Note: description edited afterwards with more information

tsengwoody / Access8Math