Counter Demo #1: various SREhttp/2 counters.

Using <!-- Replace hits --> If HIT_DURATION is specified, this won't change over quickly repeated requests.	# of hits=n.a.
Using <!-- Replace count-->	n.a.
Using XCOUNT CGI-Bin counter: < img src="/cgi-bin/xcount?count1">
Using JCOUNT #exec (HTTPD SSI counter) <!-- #exec cmd="jcount?cntdemo1" -->:	1
Using Counter.REX, text mode <!-- INTERPRET FILE COUNTER.REX file=cntdemo1.cnt -->	790
Using Counter.REX, graphics mode < IMG SRC="/counter.rex?file_www=/sre2k/srehttp2/demos/cntdemo1& graphic=normal&increment=0&width=4" >