Infrastructure changes to support scoped symbols

Summary:
 - import_project_symbols supports an optional extra field, which is the
   context of the symbol.
 - Symbol query can take a symbol argument, either as a parameter or a
   URL component (so you can now jump nav to `s Zerg/rush`, for
   example).
 - Conduit method not yet updated. Will do that later.

NOTE: Not providing a context is distinct from providing an empty
context, because an empty context stands for top-level context, i.e.
functions and classes for PHP. It will not find class methods, etc. It
is possible that we should use some weird token that could not normally
be a context name to stand in for empty context.

Test Plan: Do a bunch of symbol searches.

Reviewers: epriestley

Reviewed By: epriestley

CC: nh, aran, Korvin

Maniphest Tasks: T1602

Differential Revision: https://secure.phabricator.com/D3148

src/applications/diffusion/controller/DiffusionSymbolController.php

@@ -31,6 +31,10 @@ final class DiffusionSymbolController extends DiffusionController {
     $query = new DiffusionSymbolQuery();
     $query->setName($this->name);
 
+    if ($request->getStr('context') !== null) {
+      $query->setContext($request->getStr('context'));
+    }
+
     if ($request->getStr('type')) {
       $query->setType($request->getStr('type'));
     }
@@ -122,6 +126,7 @@ final class DiffusionSymbolController extends DiffusionController {
 
       $rows[] = array(
         phutil_escape_html($symbol->getSymbolType()),
+        phutil_escape_html($symbol->getSymbolContext()),
         phutil_escape_html($symbol->getSymbolName()),
         phutil_escape_html($symbol->getSymbolLanguage()),
         phutil_escape_html($project_name),
@@ -133,6 +138,7 @@ final class DiffusionSymbolController extends DiffusionController {
     $table->setHeaders(
       array(
         'Type',
+        'Context',
         'Name',
         'Language',
         'Project',
@@ -140,6 +146,7 @@ final class DiffusionSymbolController extends DiffusionController {
       ));
     $table->setColumnClasses(
       array(
+        '',
         '',
         'pri',
         '',