Avoid confusion when reading mod_cache code. write_ and read_ often imply

network code; store_ and recall_ are more understandable prefixes in this
context.

Reviewed by:	Roy Fielding, Cliff Woolley


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@104458 13f79535-47bb-0310-9956-ffa450edef68