Go Guru support

-added Go Guru (golang.org/x/tools/cmd/guru) support.
-removed subsequently useless/redundant features.
-removed support for languages other than Go.

To sum up, we now support 3 kinds of searches: global search (in all
locations, with find and grep), guru search, and local search (in a
specified location, with find and grep).

README.txt

@@ -1,39 +1,48 @@
 gofinder
 ========
 
-The gofinder program is an acme user interface to look for include files, specific patterns, and regexps.
-
-You need a json config file to define the projects where gofind will look; see projects-example.json for the expected fields.
-
-The resulting acme ui will look like the following.
-
-Search in: 
------------------------------------
-proj1:
-	c++:	staticMethod	staticMember	include	all
-	/home/glenda/foo	/home/glenda/bar
-proj2:
-	fortran:	module	subroutine	function	all
-	go:	package	func	all
-	/home/glenda/foobar	/home/glenda/foobarbaz	/home/glenda/go
-camlistore:
-	go:	package	func	type	method	all
-	/home/mpl/gocode/src/camlistore.org	/home/mpl/go	/home/mpl/gocode/src/github.com/mpl	/home/mpl/gocode/src/bitbucket.org/mpl	/home/mpl/git/go
-	.*zembed_.*
------------------------------------
-
-All searches are 2-1 chords: one first selects with button 1 the queried terms in the code, and one then presses and holds button 2 on one of the words of this ui and presses button 1 while still holding button 2.
-
-For each project, each language and its possible search methods are displayed, as well as the possible locations.
-For example, say the fortran module named "foo" is used and defined in proj2. Then selecting foo in the code and chording it 2-1 on the "module" word on the fortran line of proj2 will try and find the location of this module definition. 
-
-The "all" keyword/command will trigger a regexp search (only in the relevant files for the corresponding language - this is hardcoded) of whatever is chorded 2-1 to it.
-
-Same behaviour for the locations, except the search will apply to all the relevant files of the project (defined by the "Exts" field) in the chorded location.
-
-The "Excluded" field (regexp) obsiously indicates what should be excluded from the search.
-
-Limitations:
--It does not do chained calls. But I found I don't really need it, at least with Go.
-
--The underlying searches rely on find and grep. They should be replaced with native go code.
+The gofinder program is an acme user interface to search through Go projects.
+
+It uses 2-1 chording (see https://swtch.com/plan9port/man/man1/acme.html).
+It uses a JSON configuration file to define project(s) to search on; see
+projects-example.json for a working configuration example.
+
+It displays, in the following order: The name of the project, to perform a
+global search. The Go Guru (golang.org/x/tools/cmd/guru) modes, to perform a
+guru search. The project's locations, to perform a local search. For example,
+with the provided projects-example.json, the UI will look like:
+
+	Search in: 
+	-----------------------------------
+	camlistore:
+		callees	callers	callstack	definition	describe	freevars	implements	peers	pointsto	referrers	what	whicherrs
+		/home/mpl/src/camlistore.org	/home/mpl/src/camlistore.org/vendor	/home/mpl/src/go4.org	/home/mpl/src/github.com/mpl
+	-----------------------------------
+
+
+The configuration file is mapped to a project type, which is defined as follows:
+
+	type Project struct {
+		// Name is the one word name describing the project, that will appear at
+		// the top of the UI. One word, because chording on the name starts a
+		// global search in the project. Global search means a find on all the
+		// files ending with the extensions defined in Exts, looking in the
+		// locations defined in Locations, excluding all the patterns defined in
+		// Excluded. The results are piped to a grep for the argument that is sent
+		// with the chord.
+		Name      string
+		// Locations defines all the locations relevant to the project, and as
+		// such, they are displayed on the UI. A global search runs find through
+		// all of them. A chording on one of the locations will perform a local
+		// search, i.e. in the same way as a global search, except find will only
+		// run through that one location.
+		Locations []string
+		// Exts defines the file extension patterns (regexp), that find will
+		// take into account. It defaults to []string{"\.go"} otherwise.
+		Exts      []string
+		// Excluded defines the patterns (regexp), that find will take into
+		// account to exclude from the search results.
+		Excluded  []string
+		// GuruScope is the scope that guru will use for the modes that need one.
+		GuruScope []string
+	}