Normalise the use of "regexp(s)" vs "regex(es)".

"regex" won the Google battle.

vimperator/NEWS

@@ -167,7 +167,7 @@
     * add :pagestyle command to allow for switching between alternate style sheets
     * add :b# to select the alternate buffer
     * add :tabduplicate command
-    * new 'urlseparator' option for specifying the regexp used to split the arg to
+    * new 'urlseparator' option for specifying the regex used to split the arg to
       :open, :tabopen and :winopen
     * :set editor now accepts quoting/escaping to use an editor with spaces in the path
     * support for :%foo as a count for commands (not yet widely used)

vimperator/locale/en-US/autocommands.txt

@@ -40,7 +40,7 @@ Available {events}:
 
 {pat} is a regular expression, use .* if you want to match all URLs.
 
-Note: This differs from Vim which uses a glob rather than a regexp for {pat}.
+Note: This differs from Vim which uses a glob rather than a regex for {pat}.
 
 The following keywords are available where relevant:
 

vimperator/locale/en-US/index.txt

@@ -321,7 +321,7 @@ section:Options[option-index]
 ||'smartcase'|| Override the 'ignorecase' option if the pattern contains uppercase characters +
 ||'suggestengines'|| Engine Alias which has a feature of suggest +
 ||'titlestring'|| Change the title of the window +
-||'urlseparator'|| Set the separator regexp used to separate multiple URL args +
+||'urlseparator'|| Set the separator regex used to separate multiple URL args +
 ||'usermode'|| Show current website with a minimal style sheet to make it easily accessible +
 ||'verbose'|| Define which info messages are displayed +
 ||'visualbell'|| Use visual bell instead of beeping on errors +

vimperator/locale/en-US/options.txt

@@ -755,8 +755,8 @@ ____
 |\'urlseparator'|
 ||'urlseparator'|| string (default: ",\s")
 ____
-Set the separator regexp used to separate multiple URL args. Multiple arguments
-can be specified for [c]:open[c], and similar commands, using this regexp as
+Set the separator regex used to separate multiple URL args. Multiple arguments
+can be specified for [c]:open[c], and similar commands, using this regex as
 the separator. Using whitespace alone is not generally useful since it is often
 contained in a single argument. E.g. [c]:open linus torvalds[c] should perform
 a single search for the key words "linus" and "torvalds"
@@ -806,7 +806,7 @@ ____
 List of file patterns to ignore when completing files. E.g. to ignore object
 files and Vim swap files [c]:set wildignore=".*\.o,\..*\.s[a-z]\\{2}"[c]
 
-Note: Unlike Vim each pattern is a regexp rather than a glob.
+Note: Unlike Vim each pattern is a regex rather than a glob.
 ____
 
 
@@ -852,7 +852,7 @@ ____
 ____
 (default: [\.,!\?:;/\\"\^\$%&?\(\)\[\]\\{\\}<>#\\*\+\\|=~ _\\-])
 
-A regexp which defines the word separators which are used for the
+A regex which defines the word separators which are used for the
 'hintmatching' types "wordstartswith" and "firstletters" to split the words in
 the text of a link.
 ____

vimperator/locale/en-US/pattern.txt

@@ -2,7 +2,7 @@ heading:Text{nbsp}search{nbsp}commands[text-search-commands]
 
 Vimperator provides a Vim-like interface to Firefox's standard text search
 functionality. There is no support for using regular expressions in search
-commands as Firefox does not provide native regexp support. It is unlikely that
+commands as Firefox does not provide native regex support. It is unlikely that
 this will ever be available.
 
 |/| +

vimperator/locale/en-US/repeat.txt

@@ -35,7 +35,7 @@ ____________________________________________________________________________
 ||:mac[ros] [a][pat][a]|| +
 ________________________________________________________________________________
 List recorded macros matching the optional regular expression [a][pat][a]. If
-no regexp is given, list all macros.
+no regex is given, list all macros.
 ________________________________________________________________________________