REPL fails on startup on Windows machines.

[JordanRickman]

On startup, the REPL looks for its history file at .sibilant.history in the user's home directory. See repl.sibilant line 12: (var ... HISTORY-FILE (|> process.env.SIBILANT-REPL-HISTORY-FILE (or (""process.env.HOME"/.sibilant.history")))

However, on Windows machine this may fail because process.env.HOME is not set by default. Windows does not set this environment variable unless the user explicitly does so, using the environment variable USERPROFILE instead. This results in an error like the following:

Error: ENOENT: no such file or directory, open 'undefined/.sibilant.history'
    at Object.openSync (fs.js:462:3)
    at Object.<anonymous> (C:\<redacted>\stitch-sibilant-challenge\node_modules\sibilant\maps\src\repl.sibilant:26:12)
    at Module._compile (internal/modules/cjs/loader.js:1137:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)
    at Module.load (internal/modules/cjs/loader.js:985:32)
    at Function.Module._load (internal/modules/cjs/loader.js:878:14)
    at Module.require (internal/modules/cjs/loader.js:1025:19)
    at require (internal/modules/cjs/helpers.js:72:18)
    at Object.cli$repl$ [as repl] (C:\<redacted>\node_modules\sibilant\maps\src\cli.sibilant:37:7)
    at Object.<anonymous> (C:\<redacted>\node_modules\sibilant\maps\src\cli.sibilant:78:8)

A better approach would be to use Node's os.homedir() instead of process.env, as os.homedir() is more reliable across multiple OSes and environments.