Only allow proper identifiers as strings keys

[kurthuwig]

The old code checked if key and text are identical, which made no sense as there is no such limitation. On the other hand it allowed keys like "test-key" which are invalid on Android.

The new code checks if the identifier starts with an ASCII letter or underscore and only contains ASCII lettes, digits or underscores.

[Alex009]

EqualStringKeysException make sense - on string equality works logic on iOS for case when in specific language not exist some value - will be used from base locale.

for additional checks of keys - thanks :)

[kurthuwig]

EqualStringKeysException make sense - on string equality works logic on iOS for case when in specific language not exist some value - will be used from base locale.

for additional checks of keys - thanks :)

I am confused: my understanding is that if the key does not exist in a language, then the base's entry is for this key is used.
Except for GNU's gettext I have not seen using the value for looking up translations for a long time. AFAIK even on iOS keys are used to look up values in specific languages.

Can you please pinpoint me to any documentation or code that uses the values associated with the keys to look up things in other maps?

[ExNDY]

Thank you for idea, we reuse your check logic of key validation for actual generation mechanic.
will be implemented in 0.24.0-alpha-6

[Alex009]

this change was done in #575