Replace most invocations of fail keyword with die! macro
test cases, cleanup
more cleanup
cleanup for make check
Remove fail keyword from lexer & parser and clean up remaining calls to
fail

Fix merge conflicts - Issue 4524
Merge pull request #4720 from jbclements/syntactic-cleanup

Syntactic cleanup
Merge remote-tracking branch 'nickdesaulniers/issue4524' into nocomm1
README.txt: Mention linenoise
Fix breakage
automated merge
README.md, mention curl not wget.
automated merge
Tweak the CONTRIBUTING.md file.
automated merge
check-fast fallout from removing export, r=burningtree
rustdoc: Remove definitions of spawn_listener and spawn_conversation
rustdoc: Fix some search-and-replace fallout
rustdoc: Remove another use of oldcomm
rustdoc: Remove stray mode
rustdoc: Convert to pipes