reflow0.5.2

• reflowlet: terminate on 10-minute idle time (since AWS does secondly billing)
• syntax: fix digest for ExprApply
• syntax: {files,dirs}.Copy: return a helpful error message if URL scheme is missing
• runner: improve stealer allocation
• eval: scramble digest when an OpVal carries an error
• syntax,types: fix type environment for recursive module instantiations
• reflow shell: new command to shell into an exec
• tool: use stdout for reflow doc output
• tool: disable -gc for v1 flows, -dir alias for -localdir, for backwards compatibility
• reflow logs -f: support for tailing ongoing exec logs
• tool: restore noexterncache flag
• syntax: always sort map keys carefully before digesting
• syntax: fix environment persistence for declarations
• doc: add language overview docs
• config: add "local" configuration provider for user
• eval: print full image name in debug logs
• syntax: add few missing cases for trailing commas
• syntax: add a semicolon at the end of a file if there is a missing newline
• syntax: add arbitrary precision float, conversion between int and float
• eval: add option/flag -recomputeempty to recompute empty cache values