Add some aliases for re-related functions

[Yuan Fu <casouri@gmail.com>]

While debating whether it’s effective to add prefixes to increase discoverability, lets start with incremental and uncontroversial changes. Let’s start from re-related functions since it seems that many people agree on this. Here is a list of functions that I think could benefit from an alias. 

replace-regexp-in-string	re-replace-in-string
replace-match			re-replace-match
string-match			re-search-in-string
string-match-p			re-match-in-string-p
match-string			re-matched-string
match-string-no-properties	re-matched-string-no-properties
match-beginning			re-match-beginning
match-end			re-match-end

looking-at			re-match-after-point
looking-back			re-match-before-point
looking-at-p			re-match-after-point-p
posix-search-forward		re-posix-search-forward
posix-search-backward		re-posix-search-backward
posix-looking-at		re-posix-looking-at
posix-search-in-string		re-posix-search-in-string

Let’s do it like this: if you don’t like adding alias to a certain function (strongly), call it out and we will remove it from the list for now. Then we should have a small list that everybody agrees upon (or at least no one absolutely hates). 

And please do not drift the topic away in this thread, which hinders the original purpose of the thread. Let’s focus on these functions and only these functions.

Yuan