Merge Prepare: Rearrange project file to make it more merge-able

In preparation for use as Pull Request #32 on:
http://github.com/Chris7/Mudlet2/mudletDev reorganise src.pro so that it
more closely matches my branch
http://github.com/Slysven/Mudlet2/mudletDev_fileLocation
which is lined up as Pull Request #31 on the same one of Chris's branch.

There should not be any change in overall functionality (the qmake'ed
Makefile should produce the same executable both before and after this
commit).

Signed-off-by: Stephen Lyons <slysven@virginmedia.com>
Tweaks: some small changes to custom line drawing code

Change the circles around custom line points when selected to be solid
instead of dotted - looks better under a wider range of room and exit
size settings.  Simplify the target drawing code to indicated the target
room of a custom exit line - also looks better.

Added code for the first segment of a custom exit line, was previously
explicitly not handled because of the extra code that it would require.

Status bar messages for various custom line exit situations extended to
cover corner cases.

NB. StatusBar is NOT currently showing on at least Qt 5.1 / GNU/Linux
platform.  A code lines or two is needed in mudlet.cpp to generate it.

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