Changed to better error message for buyram

add custom error messages to secondary index get

fix multiple bugs that were only exercised with malicious blocks

fix llvm dependency from xenial to bionic on ubuntu:18.04

Gh#3715 stack alloc

name_suffix and eosio.system_tests improvements

Old version was more difficult to decipher and also did not work for 13
character names.

Confirmed that the old version and new version behave the same way with
randomly generated names that are no greater than 12 characters. (That
code is not in this commit.)

Sanitize the return value of memcmp() to wasm

Got rid of most warnings, cleaned eosio_system_tests, added more rmvproducer checks

For wasm’s memcmp, we farm it out to the system's memcmp, however the c specification states that memcmp only needs to return less than 0, 0, or greater than 0. It's implementation specific how much less than or greater than 0 it is. So, sanitize the return value to only ever be -1, 0, 1.

upgrade to appbase which handles newlines in options

bios-boot-tutorial: fix unlock timeout #3698

default_target_block_cpu_usage_pct increased to 10% #3694

cleos newaccount: require either --buyram-bytes or --byuram-eos, allow to delegate nothing

remove private data from deprecation log message

Build option -s CORE_SYMBOL_NAME