Handle compiler-generated suffixes in Ada names

The compiler may add a suffix to a mangled name.  A typical example
would be splitting a function and creating a ".cold" variant.

This patch changes Ada decoding (aka demangling) to handle these
suffixes.  It also changes the encoding process to handle them as
well.

A symbol like "function.cold" will now be displayed to the user as
"function[cold]".  The "." is not simply preserved because that is
already used in Ada.