Move implementations into impls/ dir

- Reorder README to have implementation list after "learning tool"
  bullet.

- This also moves tests/ and libs/ into impls. It would be preferrable
  to have these directories at the top level.  However, this causes
  difficulties with the wasm implementations which need pre-open
  directories and have trouble with paths starting with "../../". So
  in lieu of that, symlink those directories to the top-level.

- Move the run_argv_test.sh script into the tests directory for
  general hygiene.

.gitignore

@@ -4,6 +4,7 @@
 .cargo
 .config
 .mal-history
+.mal_history
 .crystal
 .lein
 .m2
@@ -12,138 +13,10 @@
 .npm
 .node-gyp
 package-lock.json
-.elm
 */experiments
-*/node_modules
-*.o
-*.pyc
-*/step0_repl
-*/step1_read_print
-*/step2_eval
-*/step3_env
-*/step4_if_fn_do
-*/step5_tco
-*/step6_file
-*/step7_quote
-*/step8_macros
-*/step9_try
-*/stepA_mal
-*/mal
+node_modules
 */notes
 
 logs
 old
-
-ada/obj/
-awk/mal.awk
-bash/mal.sh
-clojure/mal.jar
-clojure/target
-clojure/.lein-repl-history
-coffee/mal.coffee
-cs/*.exe
-cs/*.dll
-cs/*.mdb
-d/*.o
-elixir/_build
-elixir/deps
-elixir/erl_crash.dump
-elixir/*.ez
-erlang/ebin
-erlang/.rebar
-erlang/src/*.beam
-es6/mal.js
-es6/.esm-cache
-factor/mal.factor
-fantom/lib
-forth/mal.fs
-fsharp/*.exe
-fsharp/*.dll
-fsharp/*.mdb
-go/step*
-groovy/*.class
-groovy/mal.jar
-haskell/*.hi
-haskell/*.o
-haxe/*.n
-haxe/*.py
-haxe/cpp/
-haxe/*.js
-java/mal.jar
-java/target/
-java/dependency-reduced-pom.xml
-.npm/
-.node-gyp/
-js/mal.js
-js/web/mal.js
-kotlin/*.jar
-kotlin/.idea
-kotlin/*.iml
-lua/lib
-lua/linenoise.so
-lua/mal.lua
-make/mal.mk
-mal/mal.mal
-matlab/octave-workspace
-miniMAL/mal.json
-nim/nimcache*
-objc/*.d
-ocaml/*.cmi
-ocaml/*.cmo
-ocaml/*.swp
-ocaml/*.cmx
-ocaml/*.o
-ocaml/mal_lib.*
-objpascal/*.o
-objpascal/*.ppu
-objpascal/pas-readline
-objpascal/regexpr/Source/RegExpr.ppu
-perl/mal.pl
-perl6/.precomp/
-php/mal.php
-php/mal-web.php
-ps/mal.ps
-python/mal.pyz
-r/mal.r
-ruby/mal.rb
-.cargo/
-rust/target/
-rust/Cargo.lock
-rust/.cargo
-r/lib
-scala/mal.jar
-scala/target
-scala/project
-skew/*.js
-tcl/mal.tcl
-vb/*.exe
-vb/*.dll
-vimscript/mal.vim
-clisp/*.fas
-clisp/*.lib
-basic/step0_repl.bas
-basic/step1_read_print.bas
-basic/step2_eval.bas
-basic/step3_env.bas
-basic/step4_if_fn_do.bas
-basic/step5_tco.bas
-basic/step6_file.bas
-basic/step7_quote.bas
-basic/step8_macros.bas
-basic/step9_try.bas
-basic/stepA_mal.bas
-basic/*.prg
-common-lisp/*.fasl
-common-lisp/*.lib
-common-lisp/images/*
-common-lisp/hist/*
-livescript/*.js
-!livescript/node_readline.js
-livescript/node_modules
-elm/node_modules
-elm/elm-stuff
-elm/*.js
-!elm/node_readline.js
-!elm/bootstrap.js
-wasm/*.wat
-wasm/*.wasm
+tmp/

.travis_test.sh

@@ -7,7 +7,7 @@ IMPL=${2}
 
 # Environment variable configuration
 BUILD_IMPL=${BUILD_IMPL:-${IMPL}}
-TEST_OPTS="${TEST_OPTS} --debug-file ../${ACTION}.err"
+TEST_OPTS="${TEST_OPTS} --debug-file ../../${ACTION}.err"
 
 if [ "${DO_SELF_HOST}" ]; then
     MAL_IMPL=${IMPL}
@@ -55,9 +55,9 @@ build)
     # rpython often fails on step9 in compute_vars_longevity
     # so build step9, then continue with the full build
     if [ "${BUILD_IMPL}" = "rpython" ]; then
-        ${MAKE} -C "${BUILD_IMPL}" step9_try || true
+        ${MAKE} -C "impls/${BUILD_IMPL}" step9_try || true
     fi
-    ${MAKE} -C ${BUILD_IMPL}
+    ${MAKE} -C "impls/${BUILD_IMPL}"
     ;;
 test|perf)
     [ "${ACTION}" = "perf" ] && STEP=