15c68455ec
These changes make `HyREPL` use a single `HyASTCompiler` instance, instead of creating one every time a valid source string is processed. This change avoids the unnecessary re-initiation of the standard library `import` and `require` steps that currently occur within the module tracked by a `HyREPL` instance. Also, one can now pass an existing compiler instance to `hy_repl` and `hy_compiler`. Closes hylang/hy#1698.