These changes allow many improvements :
- they fix the infinite refresh of the library due to the multiple
"bookChanged" signal emitted when several operations on books were
performed simultaneously (launch several downloads)
- the scroll isn't reset to the top of the list when starting a download at
the bottom of the list
- (better optimization ?)
Now methods that concern only one book emit the signal "oneBookChanged"
with the id of the book, the JS slot search by id the correspondent book in
its list and replace it with an updated one.
Qt seems to disconnect every signal handlers (signal emitted by QCompleter)
of QLineEdit (the SearchBar) every time the QLineEdit loses the focus,
so it has to be connected every time it gains the focus with the mouse.
To align vertically the flexboxes of the same column when the window is too
small, set the flexbox property "overflow" to "hidden" allows all these flexboxes
to have the same width no matter what its content
When the download of a book finishes while the cancel's dialog is opened
and then that the user confirms the deletion of the book, the app crashes
because aria2 can't find the active download (which is already complete).
Pause the download before opening the dialog and check the download's status
before cancel it avoid this crash.
Check if there is a library.xml file in the binary directory, in this case,
set the m_libraryPath with the current binary path, otherwise set with the
default data directory. This member variable is used every time we want to
change the library's content.
Re-use the connect with openCompletion method that works fine to handle mouse
click and enter key press to open article
Remove the openTitle method that is no longer usefull.
Check the available storage before the start of a download thanks to
QStorageInfo::bytesAvailable(), if the book size is bigger than this value
an alert message appears.
The buffers, where reply of a request is send, were deleted when they were about
to close but it makes the app crash, they have to be deleted when the request
object is deleted
