transform: Fix Group::move_handle() to only move the desired handles

DiaObject::move_handle() method has some constraints, i.e it must be
reversible by moving back exactly that handle to the previous position.
To accomplish this restrict the minimum size of the transformed group
and calculate a matrix to keep the opposite handle position fixed.

Also rename array Group::resize_handles to just Group::handles.
Fix DiaColorSelector via 'More...' to not destroy the wrong widget
[unit test] add more bounding box tests

which helped debugging the recent fix
[unit test] various improvements to test-objects

 - fix typos and misleading comments
 - prefer g_assert_cmpfloat() over g_assert() because it gives more
   information on failure
 - remove most of the filtered objects from _test_movement() now that
   another bounding box miscalculation is gone
 - check if reversed DiaObject::move_handle() is restoring the original
   object bounding box (as it should)
[gtk-deprecated] Fix endless loop with grid stepping

commit 5a788e5ebe93b72a787319d1204f72ebb9aabd0a introduced a potential
endless loop with grid_step() and DiaRuler to "compensate for missing
5 and 6 in 3,4,..,7,8 major ticks". The rounding problem can be solved
more correctly with ROUND(), rather than potentially doing the same
step over and over again.
Bug 737255 - don't mess with localedir

According to  Pacho Ramos https://bugzilla.gnome.org/show_bug.cgi?id=737255
[warningectomy] Remove unused variable
[warningectomy] No previous prototype (missing static)

../../lib/prop_pixbuf.c:200:1: warning: no previous prototype for '_make_pixbuf_type_name' [-Wmissing-prototypes]
 _make_pixbuf_type_name (const char *p)
 ^
Updated Norwegian bokmål translation.
Updated Spanish Translation
Updated Czech translation
Updated Indonesian translation
[cleanup] remove superfluous prototype and comment
Cosmetic update of PyDiaObjects.dia
[transform] svg: more transformation support for Standard objects

New optional method DiaObject::transform() to apply an affine transformation
to the object. Immediately visible effect - without SVG - is rotation support
for 'Standard - Box' and 'Standard - Ellipse'.
'Standard - Text' and 'Standard - Image' are not fully supported yet, because
they require significant work on the renderer level.
Standard - Arc, Outline and ZigZagLine are not included because they wont be
used from SVG and the direct support is considered pointless.

Currently the intended main use-case is improved transformation from SVG
especially on the level of single elements. The included test file
transform-variations.svg shows the issues solved and open.
[unit test] check bounding box calculation vs. path drawing

The use of DiaPathRenderer in _test_draw() is now hidden behind a call to
create_standard_path_from_object(). This way the 'bounds' of the drawing
can be measured indirectly.
Convert to path is supposed to create an equivalent representation which
should produce the same (or smaller) bounding box as the original object.

The exception list is currently pretty long, so there is definitely room
for improvement. With smaller default tolerance value the list would be
much longer. And finally it would be nice to not only check if the bounding
box is big enough, but also if is close to what's really needed. But this
initial version should help catching regressions already.
[warningectomy] unused const variable

node.c:58:21: warning: unused variable 'NODE_BORDERWIDTH'
      [-Wunused-const-variable]
static const double NODE_BORDERWIDTH = 0.1;
                    ^
node.c:60:21: warning: unused variable 'NODE_FONTHEIGHT'
      [-Wunused-const-variable]
static const double NODE_FONTHEIGHT = 0.8;
                    ^
2 warnings generated.
Bug 737254 - Use AC_CONFIG_HEADERS instead of AC_CONFIG_HEADER

Could not find any documentation for the later, we can not use
AM_CONFIG_HEADER long time deprecated, finally gone.
[warningectomy] format string is not a string literal

Sprinkle G_GNUC_PRINTF() to avoid the following warnings and get some new ones.

message.c:180:38: warning: format string is not a string literal [-Wformat-nonliteral]
  len = g_printf_string_upper_bound (fmt, args);
                                     ^~~
message.c:190:18: warning: format string is not a string literal [-Wformat-nonliteral]
  vsprintf (buf, fmt, args2);
                 ^~~
dialib.c:46:38: warning: format string is not a string literal [-Wformat-nonliteral]
  len = g_printf_string_upper_bound (fmt, args);
                                     ^~~
dialib.c:57:18: warning: format string is not a string literal [-Wformat-nonliteral]
  vsprintf (buf, fmt, args2);
                 ^~~
diacontext.c:162:27: warning: format string is not a string literal [-Wformat-nonliteral]
  msg = g_strdup_vprintf (format, args);
                          ^~~~~~
diacontext.c:181:27: warning: format string is not a string literal [-Wformat-nonliteral]
  msg = g_strdup_vprintf (format, args);
                          ^~~~~~
[warningectomy] format string is not a string literal (potentially insecure)

dia_xml.c:286:35: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
    dia_context_add_message (ctx, error_xml->message);
                                  ^~~~~~~~~~~~~~~~~~
diacairo-print.c:248:20: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
    message_error (error->message);
                   ^~~~~~~~~~~~~~
xfig-export.c:275:21: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
    message_warning(renderer->warnings[warning]);
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~
load_save.c:1255:19: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
          message_error (error->message);
                         ^~~~~~~~~~~~~~
commands.c:507:35: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
    dia_context_add_message (ctx, error->message);
                                  ^~~~~~~~~~~~~~