Re-positioning compiler attributes

[Rik]

1/3/16

All,

I've done a trial changeset to start moving compiler attributes to the
start of declarations.  This will eventually allow us to use standardized
C++ compiler attributes rather than compiler-specific ones like
__attribute__ for gcc or __declspec for MSVC.  The results are here
http://hg.savannah.gnu.org/hgweb/octave/rev/e3b3bb522d62.

There was no particular coding standard that looked best.  When possible,
particularly in header files with only declarations, I tried to get
everything on one line.  If that didn't work, I put all the qualifiers on
one line and the return type and function name on the next line.  In .cc
files I tried a 3-line style with attributes on the first line, return type
on the next line, and the function name and arguments on the third.

--Rik