Open a project in read-only mode

[Benoît Minisini <benoit.minisini@xxxxxxxxxxxxxxxx>]

Hi,

In the last commit, I have added a button in the open project dialog 
that allows to open a project in read-only mode.

The recent file list has been updated so that it remembers if a project 
has been opened in read-only mode, and an emblem is added on the project 
icon in recent file lists or menus when this is the case.

The recent file list settings file format has changed, and is 
automatically converted to the new format.

You should not normally lose it, but you may want to save it before 
updating your IDE. It's normally located in 
'~/.config/gambas3/gambas3.recent.conf'.

Please report any problem as usual.

Regards,

--
Benoît Minisini.