Pointer movement is ignored when the `space` key is held.
To ensure [Screenshot Tool](https://extensions.gnome.org/extension/1112/screenshot-tool/) extension compatibility, we need a way to let the third extension select the screenshot area with pointer but without leaving drawing mode and without drawing.
As a side effect, it allows to insert straight line segments in free drawing (after releasing the key).
Fixes issue #20
St.Entry clutter_text set the DEFAULT cursor on leave event with a delay and overrides the cursor set by area.updatePointerCursor().
In order to update drawing cursor on menu closed, we need to leave the saveEntry before closing menu.
Since escape key press event can't be captured easily, the job is done in the menu close function.
* Use a "drawOnYourScreen" subdir in the xdg user data dir
* Info item with the name of the last saved/open json file
* "Open drawing" sub menu with data dir content
* "Save drawing" sub menu with entry
* "Save", "Open previous" and "Open next" keybindings
* Set 'max-height' property to menu actor.
* Reduce size of menu items.
* Rename 'draw-on-your-screen-menu-separator' style class to 'draw-on-your-screen-menu-separator-item' because it is relative to the item actor, not the item._separator actor.
* Rename 'draw-on-your-screen-separator' style class to 'draw-on-your-screen-helper-separator' not to confuse with menu separator.
* use var to export extensionJs.manager
* remove duplicated (old) buildPrefsWidget
* set OsdWindow.HIDE_TIMEOUT in a try/catch because HIDE_TIMEOUT is not exported with 'var'
* capture i in callbacks in for(){} (i is changing)
* add 3.24 version as supported
* GS 3.34 compatibility for barLevel, see for example status/volume.js StreamSlider.getLevel():
* 3.32 : "return 100 * this._stream.volume / this._control.get_vol_max_norm();"
* 3.34 : "return this._stream.volume / this._control.get_vol_max_norm();"
* allow 0 px lineWidth because stroke lines cannot have color with some transparency
* use warning color in OSD and drawing menu when lineWidth is 0 px
* PanelMenu.Button actor
* PopupMenu.PopupBaseMenuItem, PopupMenu.PopupSwitchMenuItem and PopupMenu.PopupSeparatorMenuItem actor
* Slider.Slider actor and 'value-changed' signal
* PopupMenu.PopupMenuManager init params
* 'org.gnome.settings-daemon.plugins.media-keys' setting values : string -> array of strings
use Gio FileIcon instead of Pixbuf because St.Icons made with Pixbuf are
not themable
replace 'stroke' icons with 'fill' icons
bind fill and dashedLine icons with properties
In test of gnome-shell 32 (in VM), 'style-changed' was regularly emitted
during drawing, so all 'this.current...' style properties was
initialized and it was impossible to select style with 'Ctrl+...'
shortcuts.
Now style is gathered on drawing mode entered, which is by the way more
frugal.
Keep watch possible regressions.
1. in removeArea, remove area container from the right parent and do not
remove and destroy helper since helper is child of container (15556e40f4)
2. do not set area and helper position to monitor position value, since their position is relative to the container (that already have the monitor position)