Updated test database containers
Added new error codes
Fixed build problem in OSX CI
Docker images are now built automatically when they change
close#178
Separate compilation
Immediate completions are now posted through the I/O executor
Jamfiles now correctly requires C++11
Refactored the protocol and channel modules
Removed example on default completion tokens
close#23close#112
Separate error categories for common, mysql and mariadb codes.
DB "flavor" detection.
CI mechanism to run db-specific integration tests.
Recovered PCHs in cmake and made them more sane.
close#108