…udlet#4608)

This PR will also allow colors for open/closed/locked doors to be
customised in the future (by adjusting the new `T2DMap` `QColor`
members: `mOpenDoorColor`, `mClosedDoorColor` and `mLockedDoorColor`.

Moved the `QMap<int, QPoint> mAreaExitsList` member out of the class header
- it is now a local `areaExitsList` value held in the `paintEvent(...)`
method and passed by reference to a couple of paint helper methods.

Revise the code that painted exit stubs as the formulas being used to work
out the inner and outer points on the line were wrong - and as they were
dependent on the room size the stubs changed as the room size did. Since
we may now be painting a door marker on them it is easier if the length is
constant and does not depend on the room size.

Since we are now able to show door markings on custom exit lines (including
on special exits) and stub exits the tool-tips in the room exits control
panel is updated to now reflect this.

This will close Mudlet#499 and close Mudlet#668 and address an issue that Fuligin
raised in the Discord # help channel on 2021/01/08 .

BugFix -  revise handling of area exits with doors:

This actually doubles the amount that area exits stick out from the
starting room and revises the drawing code so that it is not so dependent
on the room size (which modified the `exitWidth` local that the code was
using). The particular detail that required this commit was that the way
that the underlying line was drawn that was used to derive the door symbol
from had the start and end points the opposite way around to that which I
had developed the code for!

Whilst cleaning things up I spotted that there was a redundant conversion
from a `QPointF` to a `QPoint` and then back to a `QPointF` when handling
the area exit click location - that is used to record when an area exit is
(double) clicked upon to initiate a speedwalk to the room in the adjacent
area.

Revised - provide "pair of doors" representation for doors on 2D Map

As requested during review.

Revised -  tweak some aspects of the door markings

Make them a bit (150%) thicker and a little longer.

Revised - use QLineF/QPointF instead of QLine/QPoint to pacify clang-tidy Bot

It seemed to be unhappy about "narrowing conversions" of `double`s to
`int`s. when a local line and point with integer coordinates are created
- and which are then used to create others which have floating point
values.

Signed-off-by: Stephen Lyons <slysven@virginmedia.com>

I conceived of this without being aware that the change in part of Mudlet#4608
that stopped drawing the entire exit line between two rooms both visible in
the mapper twice (once for each room) had been reverted by Mudlet#5949.

This is a suggested alternative that goes back to drawing the half a line
from each room towards the other room but additionally draws the other
section stating as fully opaque but fading to transparent at the far room.
If both rooms are visible this will be hidden by the corresponding fully
visible exit line from the other room - but not if not.

It is a bit more complex to do than might be first thought because the
`QPainter::drawLine(...)` methods only use the `QPainter`'s pen (otherwise
used to draw the outline of a shape) and a gradient shading effect only
applies to the brush (fill) of a shape. This means that the line has to be
constructed as a rectangle - and to draw it at an angle it needs to be done
with `QPainter::drawPolyon(...)` using a `QLinearGradient` as the brush and
no pen.

Signed-off-by: Stephen Lyons <slysven@virginmedia.com>

This is to allow existing map files that were not laid out to accommodate
them to still use the previous smaller ones.

The large arrows came about as a side effect of my adding door markings to
more exits (and stubs) in Mudlet#4608.

Signed-off-by: Stephen Lyons <slysven@virginmedia.com>

* Fix: allow the large 2D map area exit arrows to be reverted

This is to allow existing map files that were not laid out to accommodate
them to still use the previous smaller ones.

The large arrows came about as a side effect of my adding door markings to
more exits (and stubs) in #4608.

Signed-off-by: Stephen Lyons <slysven@virginmedia.com>

* Revise: fix spelling mistake

Signed-off-by: Stephen Lyons <slysven@virginmedia.com>

* Revise: adopt peer-review suggestions

Small arrows are now the default. The user will have to ask to use the
large ones - which means that existing maps should not have an issue with
the area exit arrows now - unlike as has been reported for the 4.15.0
release version.

A scaling factor used with different values for small and large area exit
arrows has been changed to be only generated once per call to
`(void) T2DMap::paintRoomExits(...)` instead of once or twice depending on
the direction of the exit in the XY-plane.

A tooltip for this *knob* has been removed as it specifically mentioned the
version of Mudlet that introduced the large area exits - and it doesn't
need to now the default is pretty much as Mudlet would have been before
that version.

Signed-off-by: Stephen Lyons <slysven@virginmedia.com>

Co-authored-by: Vadim Peretokin <vperetokin@gmail.com>