SimGear change. It changes all the SG_xxxx to be the 'real' includes, and gets
rid of many #ifdef SG_HAVE_STD_INCLUDES. As an added bonus, rather than
replacing 'SG_USING_NAMESPACE(std)' with 'using namespace std', I just fixed
the small number of places to use std:: explicitly. So we're no longer polluting
the global namespace with the entire contents of std, in many cases.
There is one more 'mechanical' change to come - getting rid of SG_USING_STD(X),
but I want to keep that separate from everything else. (There's another
mechnical change, replacing <math.h> with <cmath> and so on *everywhere*, but
one step at a time)
- support optional <preamble> and <postamble> which are written right
after opening and before closing respectively. This can be used for a header
line or an XML header.
- unescape <preamble>, <postamble>, <format>, <line_separator>, <var_separator>
so that \t, \n, \r, \f, \v, \xnn, \nnn can be used directly (\a and \b are
ignored; use \\ for the backslash) The long names ("carriagereturn") are still
supported for <var_separator>, but one can just use \r, or \r\n too.
- don't abort when a chunk doesn't have a <node>. This is useful for adding
constant chunks which consist only of a <format>, such as XML tags.
SGPropertyNode to guarded ones. This is also done for JSBSim/JSBSim.hxx,
for which JSB had given explicit permission a while ago. I postponed that
back then, but now is the time.
