Issue warning when locale formats numbers differently from `"C"`

[marktsuchida]

See micro-manager/mmCoreAndDevices#799

In the short term, we should probably issue a Python warning when pymmcore is imported if the current locale formats numbers with a non-. decimal point -- explaining potential consequences and instructing how to set the locale to "C".

(Thanks @gselzer for discussion.)

[marktsuchida]

It should be noted that Qt has its own locale system (QLocale) that is independent of the C/C++ locale -- similar to how Java has its own locale system. So running a GUI app in "C" locale for Python, MMCore, and devices while setting Qt to the system (= user-preferred) locale might be feasible. It will require good discipline around things like number formatting and parsing, though.