The more recent version of lite-xl use the bit32 library and
the lua_Buffer functions. These function were not implemented
by the minimal compatiblity layer and are now added with this commit.

The code is adapted from:

https://github.com/keplerproject/lua-compat-5.2

There is problem with utf8 expression matching on common.utf8_chars

From PR:

https://github.com/lite-xl/lite-xl/pull/624

contributed by @dflock.

Fix regex in tokenizer

When adding a directory in a project we check if the filesystem is too
slow. If it is too slow we act as if the projects was files-limited by
the number of files but we show a specific warning.

This solution is not perfect but for very low filesystem it can limit
the problem. Otherwise the application would be totally irresponsive.

Fix a problem introduced when fixing the dirty pixel problem, commit
cb08c5cb. The node, when determining the layout was rounding the size
of the fixed-size view. In turns this latter was calling move_towards
to the default_size it wanted. If default_size was non-integer the
value vas never archieved because it was rounded during layout and
move_towars was keeping the editor busy by setting the
core.need_redraw flag.

The x size of the treeview plugin cannot really change expect if explicitly
resized.

The call to move_towards for x seems to raise a state where core.redraw is
always set to true and this prevent the application to go idle.

It is seen after the introduction of the dmon directory monitoring but it
is not clear why it wasn't seen before.

On windows paths belonging to network volumes will be gives like:

\\address\share-name\path

Now the code recognize these paths and treat them correctly.

When moving to the next character, we have to consider that the current 
one might be multi-byte.

This makes its behavior similar to `string.find`.

Fixing the Node's clipping rectangle make the clipping in DocView:draw()
partially redundant. This latter is now no longer needed to clip
on the right when drawing the document's lines but it still serves to
the purpose of clipping on the left, before the gutter region.

Rouding node's size to an integer value ensure drawing are pixel
perfect in sizing.

The last column of pixel on the window's right side isn't correctly
drawn and pixels appear dirty and more noticeably when the a NagView
message was previously shown, a stripe of red pixels remains on the right.

We use now a more souding roundig scheme. Now the rectangles to clip or to
draw are passed around as Lua numbers without any rounding. In turns, when
the rect coordinates are passed to the renderer we ensure the border of the
rect are correctly snapped to the pixel's grid. It works by computing the
coordinates of the edges, round them to integers and then compute the rect's
width based on the rounded coordinates values.

Add reverse search and some related commands

Remove `plain_rfind` optimization.

Use `last_view` if `active_view` is `CommandView`.