vectorization: improve treatment of unary minus

Changes in !48 (merged) caused test failures in https://i10git.cs.fau.de/pycodegen/lbmpy/-/jobs/534348.

Also add a test for vectorized unary minus and sp.Abs, suppress a warning with older versions of randomgen and make double-precision vector RNG accurate on Clang in fast-math mode.

The errors in test_resting_fluid and test_point_force are fixed by lbmpy!63 (merged). The error in test_phi_staggered_equivalence_on_random is fixed by https://i10git.cs.fau.de/pycodegen/pygrandchem/-/merge_requests/4.

pystencils/cpu/vectorization.py

 import warnings
 from typing import Container, Union
 
+import numpy as np
 import sympy as sp
 from sympy.logic.boolalg import BooleanFunction
 
@@ -205,6 +206,7 @@ def insert_vector_casts(ast_node):
                               (new_arg, True))
             return visit_expr(pw)
         elif expr.func in handled_functions or isinstance(expr, sp.Rel) or isinstance(expr, BooleanFunction):
+            default_type = 'double'
             if expr.func is sp.Mul and expr.args[0] == -1:
                 # special treatment for the unary minus: make sure that the -1 has the same type as the argument
                 dtype = int
@@ -213,9 +215,12 @@ def insert_vector_casts(ast_node):
                         dtype = arg.dtype.base_type.numpy_dtype.type
                     elif type(arg) is TypedSymbol and type(arg.dtype) is VectorType and arg.dtype.base_type.is_float():
                         dtype = arg.dtype.base_type.numpy_dtype.type
-                expr = sp.Mul(dtype(expr.args[0]), *expr.args[1:])
+                if dtype is not int:
+                    if dtype is np.float32:
+                        default_type = 'float'
+                    expr = sp.Mul(dtype(expr.args[0]), *expr.args[1:])
             new_args = [visit_expr(a) for a in expr.args]
-            arg_types = [get_type_of_expression(a) for a in new_args]
+            arg_types = [get_type_of_expression(a, default_float_type=default_type) for a in new_args]
             if not any(type(t) is VectorType for t in arg_types):
                 return expr
             else: