adjust indentation
speed up hd2str_lua()

It is very slow that evaluating a list of strings with vim.eval().
Evaluate a string instead.
improve hd2str_lua()

Import ichizok's patch:
https://gist.github.com/ichizok/b34b2566ba526116b64a

Use table.insert() and table.concat() instead of concatenating each
byte one by one.
Merge pull request #138 from bohrshaw/diff-binary

Distinguish binary names on 32/64-bit Unix - fix #137
Improve default
Add libcall check
Improve error message
fixed make error on linux:
    make[1]: arch: Command not found
use `uname -m` to determine x86_64 or i686 machine.
Merge pull request #140 from Shougo/topic/improve-lua

improve hd2str_lua()
Merge pull request #139 from ihacklog/master

fixed make error on linux:make[1]: arch: Command not found
Improved vp_decode

changed behavior of s:hd2str to same as s:hd2str_lua
Merge pull request #141 from ichizok/improve-vp_decode

Improved vp_decode
Rename only the binary on Linux - refine #137