Tests for floating point for..from steps (#254)

--HG--
extra : transplant_source : -%B8%D3%E8%BB%2C%A3B1%D1%8B%C3%06M%16%82%F1%91%B7G

tests/run/for_from_float_T254.pyx

+__doc__ = u"""
+    >>> double_target(0, 4)
+    at 0.0
+    at 1.0
+    at 2.0
+    at 3.0
+    4.0
+    >>> double_step(0, 2, .5)
+    at 0.0
+    at 0.5
+    at 1.0
+    at 1.5
+    2.0
+    >>> double_step_typed(0, 2, .5)
+    at 0.0
+    at 0.5
+    at 1.0
+    at 1.5
+    2.0
+    >>> double_step_py_target(0, 2, .5)
+    at 0.0
+    at 0.5
+    at 1.0
+    at 1.5
+    2.0
+    >>> int_step_py_target(0, 2, 1)
+    at 0
+    at 1
+    2
+"""
+
+def double_target(a, b):
+    cdef double x
+    for x from a <= x < b:
+        print "at", x
+    return x
+
+def double_step(a, b, dx):
+    cdef double x
+    for x from a <= x < b by dx:
+        print "at", x
+    return x
+
+def double_step_typed(a, b, double dx):
+    cdef double x
+    for x from a <= x < b by dx:
+        print "at", x
+    return x
+
+def double_step_py_target(a, b, double dx):
+    cdef object x
+    for x from a <= x < b by dx:
+        print "at", x
+    return x
+
+def int_step_py_target(a, b, int dx):
+    cdef object x
+    for x from a <= x < b by dx:
+        print "at", x
+    return x