Robustness, random numbers, and TLS configuration

crew 0.5.0

• Suppress interactive browser on Windows which launched on each worker previously (@psychelzh).
• Migrate to the new host/daemon nomenclature in mirai 0.9.1 (#96).
• Suppress status() retries (@shikokuchuo, #100).
• Implement launch_max to error out if workers repeatedly launch without completing any tasks (#101, @shikokuchuo, @multimeric).
• Detect discovered workers more robustly in launcher$done().
• Add a new algorithm argument to the push(), shove(), and map() methods of controllers and controller groups, as well as arguments/fields in crew_eval() and its return value (#113, @shikokuchuo).
• As a default for pseudo-random number generation, leverage widely-spaced L'Ecuyer streams as supported by mirai::nextstream() (#115, @shikokuchuo).
• Move README documentation to vignettes.
• Add a new crew_tls() function for TLS configuration (#120).
• Deprecate the tls_enable and tls_config arguments of crew_client() etc. in favor of a tls argument which accepts crew_tls() objects (#120).