### Problem description
There are some recent issues about Mac keys not configured properly for
the pattern editor. This PR moves all the shortcuts to the shortcut
manager, so they can be edited at will. Even if the key is not
identified correctly it should be possible to use preferred keys for any
action.
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Co-authored-by: Nik <werwolv98@gmail.com>
### Problem description
Typing `--help` causes ImHex to exit without outputting anything.
Diagnostic messages from glib, ASan, other libraries that might have
something important to say, etc. are also suppressed.
### Implementation description
This effectively reverts 7c1e33dde6, which
was partially reverted only on Windows by code that was left commented
out in f114239f51.
Allowing other libraries to print to stderr may make the output ‘ugly’,
but lots of things print to stderr that are important for figuring out
why something is bugged, like ASan and glib.
### Additional things
### Problem description
The fonts list on Linux does not show all system fonts, and does not
show font names at all.
### Implementation description
Use Fontconfig to make the list less bad if Fontconfig headers are
available.
### Additional things
I like fonts.
---------
Co-authored-by: Nik <werwolv98@gmail.com>
### Problem description
#### Problem 1
In borderless mode ImHex disables the standard macOS titlebar rendering
and input processing. As a result double clicking the titlebar does not
trigger the native macOS behavior set in `System Settings -> Desktop &
Dock -> Double-click a window's title bar to [Zoom/Minimize/Do
nothing]`.
#### Problem 2
The ImHex window shows up as blank/transparent when de-minimizing it
from the dock.
#### Problem 3
Widgets experience ghost hover inputs from the past position of the
cursor during live resizing.
### Implementation description
ImGui elements consume input events in the order they are drawn. As a
result by "drawing" an `InvisibleButton` over the content area of the
titlebar we can catch unprocessed clicks in the titlebar area.
Connecting this button's double clicks to the native window is then a
trivial endeavour.
The blank windows was caused by the rendering stack clearing the GL
buffer, but proceeding to draw nothing in it. I have short circuited
this path.
Ghost hover inputs were squelched by consistently moving the ImGui
cursor to `0, 0` during a live resize. The OS will dispatch a cursor
positioning event once the resizing ends, restoring normal behavior.
### Screenshots
N/A
### Additional things
N/A
---------
Co-authored-by: Nik <werwolv98@gmail.com>
### Problem description
When the close button is clicked, `ImGui::BeginPopupModal()` sets the
bool passed into the second parameter (p_open) to false. However, the
closing logic did not take this into account, making it difficult to
actually close modal popups.
For example, closing the "Export pattern File" modal took several clicks
on the "X" button, now it closes instantly.
### Implementation description
I added an additional check for the `open` variable being `false` in the
logic that checks the closing condition.
