Implement fraction ranges and extend GstFraction to support arithmetic subtraction, as well as deserialization from i...

Original commit message from CVS:
* check/gst/capslist.h:
* check/gst/gstcaps.c: (GST_START_TEST):
* check/gst/gstvalue.c: (GST_START_TEST), (gst_value_suite):
* gst/gststructure.c: (gst_structure_parse_range),
(gst_structure_fixate_field_nearest_fraction):
* gst/gststructure.h:
* gst/gstvalue.c: (gst_value_init_fraction_range),
(gst_value_free_fraction_range), (gst_value_copy_fraction_range),
(gst_value_collect_fraction_range),
(gst_value_lcopy_fraction_range), (gst_value_set_fraction_range),
(gst_value_set_fraction_range_full),
(gst_value_get_fraction_range_min),
(gst_value_get_fraction_range_max),
(gst_value_serialize_fraction_range),
(gst_value_transform_fraction_range_string),
(gst_value_compare_fraction_range),
(gst_value_deserialize_fraction_range),
(gst_value_intersect_fraction_fraction_range),
(gst_value_intersect_fraction_range_fraction_range),
(gst_value_subtract_fraction_fraction_range),
(gst_value_subtract_fraction_range_fraction),
(gst_value_subtract_fraction_range_fraction_range),
(gst_value_collect_fraction), (gst_value_fraction_multiply),
(gst_value_fraction_subtract), (gst_value_deserialize_fraction),
(gst_value_transform_string_fraction), (_gst_value_initialize):
* gst/gstvalue.h:
Implement fraction ranges and extend GstFraction to support
arithmetic subtraction, as well as deserialization from integer
strings such as "100"
Add a testsuite as for int and double range set operations