This is the normal standard way in C, C++ as well as Java and there's no
longer any reason for ICU to be different. The various internal macros
providing custom boolean constants can all be deleted and code as well
as documentation can be updated to use lowercase true/false everywhere.
- Add updated versions of UVector::addElement() and ensureCapacity() that respect
incoming errors.
Follow on to c26aebe, which renamed the original versions.
- Add UVector::adoptElement() as a replacement for addElement() when the vector
has a deleter function set, meaning that it adopts ownership of its elements.
The intent is to make the behavior clearer at the call sites when looking
at unfamiliar code.
- Make all functions with an incoming failure, as indicated by a UErrorCode parameter,
leave the vector unchanged.
- Change all functions that store object pointers into the vector such that,
when the store cannot be completed for any reason _and_ the vector has a deleter function,
then the incoming object is deleted.
This change can simplify the error handling code around calls to the affected functions
(addElement() and insertElementAt(), in particular)
- Add index bounds checking on functions where it was possible - that is, on functions
with both U_ErrorCode and index parameters.
- Changed to more modern C++ idioms in some parts of the UVector implementation.
- Review & update as required all uses of the UVector functions
setElementAt(), insertElementAt(), setSize(), sortedInsert()
these being the functions with changed behavior on error conditions
(aside from addElement()).
This PR will be followed by more, switching call sites in various ICU services
from UVector::addElementX() (old behavior on errors)
to UVector::addElement() (new behavior on errors)
