On mingw-w64, long long (64bit wide) is larger than long (32bit wide).
Therefore we need some more specializations for string, docstring,
otextstream and << overloaded ostream functions. The configuration code
is by me, the source code changes by Shankar Giri Venkita Giri (bug 10053).
Please use the new function otexstream.append(str, texrow) to append an
odocstringstream with texrow information to the output when outputing to a
string buffer (e.g. case of subcaptions).
otexstream used to count lines to build a TexRow, and some other things. The new
class otexrowstream has the line counting feature of the previous otexstream
without other stuff. otexstream is now a subclass of otexrowstream that has the
same features as before.
This is preliminary work for extending the cursor<->row tracking to math.
This resolves a dependency of src/support/docstream.cpp on src/TexRow.cpp,
which is the wrong way round. This fixes the linking
src/tests/check_ExternalTransforms with MSVC where the linker is not clever
enough to detect that the whole otexstream class is unused.
