Improving VSX performance of integral function

* Adding support for vector get function on VSX datatypes so the
integral function gains a bit of performance.

* Removing get as a datatype member function and implementing a new HAL
instruction v_extract_n to get the n-th element of a vector register.

* Adding SSE/NEON/AVX intrinsics.

* Implement new HAL instruction v_broadcast_element on VSX/AVX/NEON/SSE.

* core(simd): add tests for v_extract_n/v_broadcast_element

- updated docs
- commented out code to repair compilation
- added WASM and MSA default implementations

* core(simd): fix compilation

- x86: avoid _mm256_extract_epi64/32/16/8 with MSVS 2015
- x86: _mm_extract_epi64 is 64-bit only

* cleanup