f make helper functions static
f hash noncedata into nonce in nonce_function_bipschnorr
f expose nonce_function_bipschnorr
f fix undefined behavior when shifting an int 31 places
f add cplusplus ifdef to schnorrsig include file
f hash complete pubkey into batch seed
f chacha20 for bigendians
f add schnorrsig to travis
f show in configure if schnorrsig is enabled