using ido and remove helm
update
add "ctexart" "ctexrep" and "ctexbook"  to `org-latex-classes
add org-latex-derived-class function
remove "twoside" class options
Revert "update"

This reverts commit 7b42aa8048b9de5181bc71746820115385c134a0.

Conflicts:
	eh-org.el
bugfix