Test whether the string is valid key, i.e. does not need escaping, is not a comment and not empty string.
assert(isValidKey("Valid key")); assert(!isValidKey("")); assert(!isValidKey(" ")); assert(!isValidKey("Sneaky\nKey")); assert(!isValidKey("# Sneaky key")); assert(!isValidKey("Sneaky=key"));
See Implementation
Test whether the string is valid key, i.e. does not need escaping, is not a comment and not empty string.