Add disasm mode setting support

[ioo0s]

Add support for Disasm mode setting.Currently only supports rust and python binding, nodejs binding will support in the near future.
#23
#20
In rust, We can set the mode for SleighBuilder（this setting is optional, default mode is 16 bit）

#[test]
fn test_x86_64_bit() {
    let mut sleigh_builder = SleighBuilder::default();
    let spec = arch("x86-64").unwrap();
    let buf = [72, 49, 192];
    let mut loader = PlainLoadImage::from_buf(&buf, 0);
    sleigh_builder.loader(&mut loader);
    sleigh_builder.spec(spec);
    // this setting is optional, default mode is 16 bit
    sleigh_builder.mode(MODE64);
    let mut asm_emit = CollectingAssemblyEmit::default();
    let mut pcode_emit = CollectingPcodeEmit::default();
    sleigh_builder.asm_emit(&mut asm_emit);
    sleigh_builder.pcode_emit(&mut pcode_emit);
    let mut sleigh = sleigh_builder.try_build().unwrap();

    sleigh.decode(0).unwrap();

    println!("{:?}", asm_emit.asms);
    println!("{:?}", pcode_emit.pcode_asms);
}

In python, the third parameter setting mode when new Sleigh(),this setting is optional also, default mode is 16 bit.

from bincraft import *
    code = [72, 49, 192]
    sleigh = Sleigh(ARCH_X86_64, code, MODE_64)
    for asm in sleigh.disasm(0):
        print(asm.mnemonic() + "\t" + asm.body())