Changes in v59..v66

BREAKAGE (needs updating Migration Guide doc)
--------

+ cef_display_handler.h
- + OnConsoleMessage: new param 'level'
- + update migration guide

+ cef_life_span_handler.h
- + OnBeforePopup: created on UI thread instead of IO thread
  - + update checks for thread
  - + update migration guide

+ cef_print_handler.h
- + Modify subprocess/print_handler_gtk.h and .cpp files
    (copy from upstream cefclient)
- + OnPrintSettings new param
- + OnPrintDialog new param
- + OnPrintJob new param
- + OnPrintReset new param

+ cef_render_process_handler.h
- + Remove OnBeforeNavigation in subprocess/cefpython_app.h and .cpp files

+ cef_request_handler.h
- + OnBeforeBrowse: new param 'user_gesture'
- + update Migration Guide

+ internal/cef_linux.h
+ internal/cef_types_linux.h
+ internal/cef_mac.h
+ internal/cef_types_mac.h
+ internal/cef_win.h
+ internal/cef_types_win.h
- + OSR windows are transparent by default. To change it set
    CefBrowserSettings.background_color .
- + CefWindowInfo (cef_window_info_t): transparent_painting_enabled option removed
- + CefWindowInfo.SetAsWindowless: 'transparent' param removed
- + Deprecate WindowInfo.SetTransparentPainting method. When set
    to True do nothing. If set to False then raise Exception
    and provide info on CefBrowserSettings.background_color.
  - + Update Migration Guide doc

internal/cef_types.h
- + cef_settings_t:
  - + javascript_open_windows option removed (keep a dummy for BC)
    - + update Migration Guide
- + cef_thread_id_t:
  - + TID_DB removed (update Migration Guide)
  - + TID_PROCESS_LAUNCHER removed (update Migration Guide)
  - + TID_CACHE removed (update Migration Guide)
  - + Added threads: TID_FILE_BACKGROUND, TID_FILE_USER_VISIBLE


+ cef_urlrequest.h
- + cef_urlrequest_flags_t:
  - + Add: UR_FLAG_ONLY_FROM_CACHE, UR_FLAG_ALLOW_STORED_CREDENTIALS,
           UR_FLAG_STOP_ON_REDIRECT
  - + Remove: UR_FLAG_ALLOW_CACHED_CREDENTIALS


NEW FEATURES
------------

internal/cef_types.h
- cef_log_severity_t: new key LOGSEVERITY_DEBUG
- cef_settings_t:
  - background_color: OSR windows can set an ARGB background color
- cef_path_key_t (informational only):
  - PK_DIR_RESOURCES new key
- cef_urlrequest_flags_t (expose in cefpython.Request.Flags):
  - UR_FLAG_ONLY_FROM_CACHE new flag
  - UR_FLAG_STOP_ON_REDIRECT new flag
  - enum values have changed due to new key
- cef_thread_id_t:
  - TID_FILE_BACKGROUND (deprecated TID_FILE)
  - TID_FILE_USER_VISIBLE
- cef_popup_features_t: some keys removed (not exposed, informational only)
- cef_referrer_policy_t changes (not exposed)

cef_accessibility_handler.h
- CefAccessibilityHandler
- CefRenderHandler::GetAccessibilityHandler

cef_render_handler.h
- OnTextSelectionChanged

cef_browser.h
- SetAccessibilityState
- SetAutoResizeEnabled
- GetExtension
- IsBackgroundHost

cef_cookie.h
- GetBlockingManager

cef_display_handler.h
- OnAutoResize
- OnLoadingProgressChange

cef_drag_data.h
- GetImage (cross-platform)
- GetImageHotspot (cross-platform)
- HasImage (cross-platform)

cef_extension.h
- CefExtension
- Will require exposing CefRequestContext object and its methods
  LoadExtension, DidLoadExtension, etc.

cef_request_context.h
- LoadExtension
- DidLoadExtension
- HasExtension
- GetExtensions
- GetExtension

cef_request_context_handler.h
- OnRequestContextInitialized

cef_extension_handler.h
- CefGetExtensionResourceCallback
- CefExtensionHandler

cef_file_util.h
- CefLoadCRLSetsFile

cef_request_handler.h
- CanGetCookies
- CanSetCookie

cef_response.h
- GetURL
- SetURL

cef_server.h
- You can easily start a web server in Python, so exposing this API
  doesn't seem to be of great value?
- CefServer: a web server that supports HTTP and WebSocket requests
- CefServerHandler

cef_v8.h
- CefV8ArrayBufferReleaseCallback
- CefV8Value new methods:
  - CreateArrayBuffer (does not own the buffer)
  - IsArrayBuffer
  - GetArrayBufferReleaseCallback
  - NeuterArrayBuffer