rm function.replace, add deep and shallow variants

[gertjanvanzwieten]

This PR removes the general function.replace decorator and replaces it with the specialized deep_replace_property (used for simplified and optimized_for_numpy) and shallow_replace (used for replace_arguments, _deep_flatten_constants and _combine_loop_concatenates). The differences between the two constructs are as follows:

@deep_replace_property

• property
• intermediate values cached in object attribute
• depth first
• recursive

@shallow_replace

• function
• intermediate values cached only during replacement
• depth last
• non recursive