TODO

* defect *

[ ] when opening large file from cmdline, the main window do not showup
    until the file is done with loading.(should load file another thread)
[ ] when restoring from snapshot, make sure the same file is only onened once,
    and is shared among multiple views.

* high priority *

[x] cleanup code and refactor, with the help of pylint
[x] make encoding per document, not a global one.
[x] git rid of the evil module: globalvalue
[x] add more support for shortcuts
[x] refine context menu
[x] remember the size and position of window
[x] start correctly when config file is missing(e.g, running for the first time)
[x] 'locate' is broken, because of the recent change of url format in PyChmWebView
[x] suport 'open recent files'
[x] support anchor in page
[ ] show useful info on statusbar, such as the link url under mouse
[ ] support showing icon with tree item(QTreeWidgetItem::setIcon)

* low priority *

[ ] sort search result in `natural` way
[ ] sort index in `natural` way
[x] support fullscreen mode
[x] support hiding side panel
[ ] support i18n and l10n
[ ] support flash

* idea *
[ ] support vi-style keybindings