Do not execute sage-shell-ac:init unless output finished.
Let sage-shell:input-history-cache-file be nil by default.
Modified sage-install-guess-sage-root.
Added variable sage-shell:use-unicode-banner.
Disable color.
The prompt of the interface gp is "pari:".
Modified sage-shell:ansi-color-filter-apply.
Added sagetex-load-file.
comint-last-prompt-overlay is not defined in Emacs 24.4.
Added keywords to fontify in the document buffer.
Added keywords to sage-shell-help:fontlock-keyword-regexp.