#!r6rs doesn't change writer mode on REPL

[Takashi Kato]

Since 0.5.6, read won't change write mode however on REPL it's inconvenient.

Export 'read-with-context' so that REPL can handle this.

[Takashi Kato]

Exported read-with-context and make-read-context Modified to use read-with-context on REPL (Fixed #54)

→ <<cset 81ee2295f005>>