include twofish implementation by Drew Csillag
fix typo in twofish implementation
add file .gitignore
Makefile rules to make sources from twofish
include sha256 implementation
move contents of sha256.h into sha256.c
Revert "move contents of sha256.h into sha256.c"

This reverts commit 800a8845471a98026723e52a6055ba15e1473f0f.
sha256, twofish: do not include headers

Header files fill be concatenated with sources in
resulting all-in-one file.
build rule for file common_lib.c
make all functions static in common_lib.c
remove sha256 tests from common_lib.c
Lua binding to twofish encrypt with sha256(key)
build rules for encrypt_lib.so
fix compilation errors
fix encryption: use sha256 instead of key itself
encryption: push result when it is ready
encryption: free memory used to calculate result
write and bind decryption function

TwoFish is used in CTR mode (stream cipher),
so decryption is similar to encryption.
fix some errors of decryption
encryption fix error

One value was used as both key and cleartext.