Change/Fix: (src) predicate

Use keyword args, fix non-sexp syntax and searching.

README.org

@@ -153,17 +153,18 @@ An =org-ql= query is a lisp form which may contain arbitrary lisp forms, as well
 
 The command =org-ql-search= also accepts, and the command =helm-org-ql= only accepts, an alternative, non-sexp query syntax.  The syntax is simple, and a few examples of queries in both syntaxes should suffice.  By default, when multiple predicates are used, they are combined with boolean =and=.
 
-| Sexp syntax                                     | Non-sexp syntax                         |
-|-------------------------------------------------+-----------------------------------------|
-| ~(todo)~                                          | ~todo:~                                   |
-| ~(todo "SOMEDAY")~                                | ~todo:SOMEDAY~                            |
-| ~(todo "SOMEDAY" "WAITING")~                      | ~todo:SOMEDAY,WAITING~                    |
-| ~(ts :on today)~                                  | ~ts:on=today~                             |
-| ~(ts-active :from "2017-01-01" :to "2018-01-01")~ | ~ts-active:from=2017-01-01,to=2018-01-01~ |
-| ~(clocked :on -1)~                                | ~clocked:on=-1~                           |
-| ~(heading "quoted phrase" "word")~                | ~heading:"quoted phrase",word~            |
-| ~(and (tags "book" "books") (priority "A"))~      | ~tags:book,books priority:A~              |
-| ~(priority >= B)~                                 | ~priority:A,B~                            |
+| Sexp syntax                                     | Non-sexp syntax                              |
+|-------------------------------------------------+----------------------------------------------|
+| ~(todo)~                                          | ~todo:~                                        |
+| ~(todo "SOMEDAY")~                                | ~todo:SOMEDAY~                                 |
+| ~(todo "SOMEDAY" "WAITING")~                      | ~todo:SOMEDAY,WAITING~                         |
+| ~(ts :on today)~                                  | ~ts:on=today~                                  |
+| ~(ts-active :from "2017-01-01" :to "2018-01-01")~ | ~ts-active:from=2017-01-01,to=2018-01-01~      |
+| ~(clocked :on -1)~                                | ~clocked:on=-1~                                |
+| ~(heading "quoted phrase" "word")~                | ~heading:"quoted phrase",word~                 |
+| ~(and (tags "book" "books") (priority "A"))~      | ~tags:book,books priority:A~                   |
+| ~(src :lang "elisp" :regexps ("defun"))~          | ~src:defun,lang=elisp~ or ~src:lang=elisp,defun~ |
+| ~(priority >= B)~                                 | ~priority:A,B~                                 |
 
 Note that the =priority= predicate does not support comparators in the non-sexp syntax, so multiple priorities should be passed instead, as seen in the last example.
 
@@ -189,7 +190,7 @@ Arguments are listed next to predicate names, where applicable.
 +  =priority (&optional comparator-or-priority priority)= :: Return non-nil if current heading has a certain priority.  ~COMPARATOR-OR-PRIORITY~ should be either a comparator function, like ~<=~, or a priority string, like "A" (in which case (~=~ will be the comparator).  If ~COMPARATOR-OR-PRIORITY~ is a comparator, ~PRIORITY~ should be a priority string.  If both arguments are nil, return non-nil if heading has any defined priority.
 +  =property (property &optional value)= :: Return non-nil if current entry has ~PROPERTY~ (a string), and optionally ~VALUE~ (a string).  Note that property inheritance is currently /not/ enabled for this predicate.  If you need to test with inheritance, you could use a custom predicate form, like ~(org-entry-get (point) "PROPERTY" 'inherit)~.
 +  =regexp (&rest regexps)= :: Return non-nil if current entry matches all of ~REGEXPS~ (regexp strings).  Matches against entire entry, from beginning of its heading to the next heading.
-+  ~src (&optional lang regexps)~ :: Return non-nil if current entry contains an Org Babel source block.  If ~LANG~ is non-nil, match blocks of that language.  If ~REGEXPS~ is non-nil, require that block's contents match all regexps.
++  ~src (&key lang regexps)~ :: Return non-nil if current entry contains an Org Babel source block.  If ~LANG~ is non-nil, match blocks of that language.  If ~REGEXPS~ is non-nil, require that block's contents match all regexps.
 +  =tags (&optional tags)= :: Return non-nil if current heading has one or more of ~TAGS~ (a list of strings).  Tests both inherited and local tags.
 +  =tags-inherited (&optional tags)= :: Return non-nil if current heading's inherited tags include one or more of ~TAGS~ (a list of strings).  If ~TAGS~ is nil, return non-nil if heading has any inherited tags.
      -  Aliases: ~inherited-tags~, ~tags-i~, ~itags~.