added --target=avx-i64x4 & svml support for all sse/avx modes

Support for --target=avxh that uses 4-lane vector. This effectively halves the single precision performance, but may result in big performance improvement for double precision heavy codes.

Wow, didn't realize that pull request tracks all the changes I do in my tree... 

Anyway, added svml support for all sse/avx modes in both double and single precision. Tested avxh in double precision only. Have to figure out to prevent this pull request tracking my branch..

changed target from avxh to --target=avx-i64x4 and mask is now i64.

update: sincos is now supported in x2 modes, except currently calls sin/cos separately instead of sincos svml intrinsic
update: floating point constants are now read as double and not floats in constexpresions (if they have "f"-suffix, they become floats)