fix typos of hex strings decoding

[Marukohe]

Hex strings encoding and decoding has been described in #513. There are some typos in res/Hex.java.

Also, I found some bugs for hex strings encoding and decoding. When I use dex2jar to translate Webmon App, an int array AppCompatTheme in androidx.appcompat.R.class is encoded as a hex string. But the decode function res.Hex#decode_B is not included in the translated jar. I added res/Hex.class to java classloader's class path and it can work.

[ThexXTURBOXx]

Very nice find! I included your fix in #486 :)

[pxb1988]

merged by #594