test/helpers: added struct dtypes support to get_test_array()
cluda/dtypes: added struct dtypes support to c_constant()
transpose.mako: removed commented code
core/transformation: not deriving KernelParameter from Type

We need to initialize ``ctype`` attribute manually and process it properly in case if it is a module.
reduce: using a dtype'd value in predicates instead of a string
test/computations/reduce: added a testcase for struct reduction
test/helpers: added support of struct dtypes to diff_is_negligible()
reduce: fixed a bug with incorrect condition on the reduction power
test/computations/reduce: added a simple performance test
reduce.mako: removed a redundant temporary variable
test/computations/reduce: added a forgotten import
cluda/dtypes: fixed logic in c_constant()
cluda/dtypes: added flatten_dtype() function
transpose: fixed crashes in case of struct dtypes
test/computations/reduce: removed nested type from test_structure_types(), there are some problems with CUDA/OpenCL
reduce.mako: simplified the code, made it work with custom structures
TODO: added a detail
TODO: added a task
Merge branch 'feature/struct-reduce' into develop