[fpc-pascal] Generic String Functions

[Marco van de Voort]

In our previous episode, Sven Barth said:
> Problem: there is (currently) no string type that can handle ANSI, UTF-8
> and UTF-16 at once. The first two are handled by AnsiString and the third
> by UnicodeString. And those two are not equal which would be important for
> overrides/overloads/inheritance. Without that your whole idea is useless.

Moreover, will operations that use character access make sense at all if you
don't know what the actual encoding is? (not only s[] but also
pos,delete,insert etc).   The same code can seem to behave differently
because different code-paths make the same parameter have different
encodings.

It will require a "forceencoding()" function etc, which is incompatible with
all current stringcode, and frustrate the general no conversion spirit which
is the main advantage.

And of course it is totally incompatible with Delphi.