Although \( is needed in docstrings in Elisp code, it is not needed in
docstrings in C code, since C function definitiions do not start with
a parenthesis.  The backslashes made the docstrings a bit harder to
read and to format in columns.  Also, some C docstrings had ( in
column 1 and this did not appear to be causing any problems.  So,
simplify C docstrings by replacing \( with ( and \) with ).

* src/floatfns.c (ceiling2, floor2, truncate2):
Assume C99 (i.e., Fortran) semantics for integer division.
This simplifies the code.

* doc/lispref/numbers.texi (Float Basics): Improve ldexp documentation.
* src/floatfns.c (Fldexp): Require 2 args.  Avoid undefined behavior
if the exponent is out of 'int' range.  Improve documentation.
Fixes: bug#20185

Run admin/update-copyright.

* doc/misc/autotype.texi (Skeleton Language):
* doc/misc/message.texi (Header Commands):
* lisp/allout-widgets.el (allout-widgets-tally)
(allout-decorate-item-guides):
* lisp/menu-bar.el (menu-bar-positive-p):
* lisp/minibuffer.el (completion-pcm-complete-word-inserts-delimiters):
* lisp/cedet/ede.el (ede-project-directories, ede-check-project-directory):
* lisp/cedet/semantic/ia-sb.el (semantic-ia-sb-show-doc):
* lisp/cedet/semantic/tag.el (semantic-tag-in-buffer-p):
* lisp/cedet/semantic/bovine/c.el (semantic-tag-abstract-p):
* lisp/gnus/gnus-registry.el (gnus-registry-install-p): Doc fix.
* lisp/progmodes/gdb-mi.el (gdbmi-same-start, gdbmi-is-number):
* lisp/progmodes/js.el (js--inside-param-list-p)
(js--inside-dojo-class-list-p, js--forward-destructuring-spec):
* lisp/progmodes/prolog.el (region-exists-p):
* lisp/progmodes/verilog-mode.el (verilog-scan-cache-ok-p):
* lisp/textmodes/reftex-parse.el (reftex-using-biblatex-p):
* lisp/url/url-parse.el (url-generic-parse-url):
* src/floatfns.c (Fisnan):
* src/profiler.c (Fprofiler_cpu_running_p):
Doc fixes (replace `iff').

Fixes: debbugs:17309

* doc/lispref/numbers.texi (Numeric Conversions, Rounding Operations):
Document that 'round' and 'fround' round to even.
* src/floatfns.c (emacs_rint) [!HAVE_RINT]: Round to even.
This way, the unusual !HAVE_RINT case acts like the usual
HAVE_RINT case, and we can fix the documentation accordingly.

Problem reported by Timothy C. Burt.
* floatfns.c (isfinite, isnan): Redefine unconditionally.

* configure.ac (log2): Check for this function.
* doc/lispref/numbers.texi (Math Functions): Remove obsolete function log10.
* lisp/subr.el (log10): Move here from C code, and declare as obsolete.
All uses of (log10 X) replaced with (log X 10).
* src/floatfns.c (Flog) [HAVE_LOG2]: Use log2 if available and if the
base is 2; this is more accurate.
(Flog10): Move to Lisp (marked obsolete there).