Make Context a class, not a struct

src/completion.hh

@@ -9,7 +9,7 @@
 namespace Kakoune
 {
 
-struct Context;
+class Context;
 
 typedef std::vector<String> CandidateList;
 

src/context.hh

@@ -20,8 +20,9 @@ class KeymapManager;
 // The Context object links an Client, an Editor (which may be a Window),
 // and a UserInterface. It may represent an interactive user window, or
 // a hook execution or a macro replay.
-struct Context
+class Context
 {
+public:
     Context();
     explicit Context(Editor& editor);
     Context(Client& client, Editor& editor);

src/hook_manager.hh

@@ -9,7 +9,7 @@
 namespace Kakoune
 {
 
-struct Context;
+class Context;
 typedef std::function<void (const String&, Context&)> HookFunc;
 
 class HookManager

src/register.hh

@@ -7,7 +7,7 @@
 namespace Kakoune
 {
 
-struct Context;
+class Context;
 
 class Register
 {