[tex-eplain] Correct format for \indexsee and \indexseealso

[John Culleton]

According to _Chicago Manual of Style_ and my inquiries on the Index-L 
listing, the following formats are correct for index items (note punctuation 
and capitalization):

foo. See bar
foo, 23, 32. See also bar
foo, 23, 32. See also bar; bell

There is also an acceptable alternative style:
foo (see bar)
foo, 23, 32 (see also bar)
foo, 23, 32 (see also bar; bell)

IMO eplain.tex should adhere to one style or the other, preferably the first.
 
I am not competent to fix the code in eplain.tex. I only point out the need. 

Probably LaTeX and Context need fixing also. 
-- 
John Culleton