Cleaner string handling
Cleaner string handling

Use `rb_enc_copy` and define RSTRING_NOT_MODIFIED for RBX. This should
speed up things.

kattybilly/redcarpet,WindStill/redcarpet,emq/redcarpet,be9/redcarpet,fukayatsu/redcarpet,gitcafe-dev/redcarpet,emiddleton/redcarpet,kaneshin/redcarpet,increments/greenmat,JuanitoFatas/redcarpet,cjlittle/redcarpet_legalcitations,emq/redcarpet,kaneshin/redcarpet,Hacker0x01/redcarpet,rkh/redcarpet,peripia/redcarpet,vmg/redcarpet,fukayatsu/redcarpet,fukayatsu/redcarpet,kevinsawicki/redcarpet,emiddleton/redcarpet,vmg/redcarpet,vmg/redcarpet,vmg/redcarpet,kattybilly/redcarpet,fukayatsu/redcarpet,peripia/redcarpet,emq/redcarpet,Hacker0x01/redcarpet,kaneshin/redcarpet,Hacker0x01/redcarpet,be9/redcarpet,gitcafe-dev/redcarpet,Hacker0x01/redcarpet,cjlittle/redcarpet_legalcitations,be9/redcarpet,kattybilly/redcarpet,peripia/redcarpet,gitcafe-dev/redcarpet,kevinsawicki/redcarpet,liquorburn/redcarpet,liquorburn/redcarpet,liquorburn/redcarpet,kaneshin/redcarpet,WindStill/redcarpet,rkh/redcarpet,be9/redcarpet,WindStill/redcarpet,liquorburn/redcarpet,JuanitoFatas/redcarpet,increments/greenmat,kattybilly/redcarpet,emiddleton/redcarpet,JuanitoFatas/redcarpet,increments/greenmat,increments/greenmat,kevinsawicki/redcarpet,emq/redcarpet,rkh/redcarpet,cjlittle/redcarpet_legalcitations