This feature only encourages poor application interactivity: anything which is
sufficiently slow to require a splash screen should be made faster instead.
In addition to that, the feature is poorly implemented (X11-specific), and thus
useless. Rip it out, and remove the last dependency on X11 from applauncherd.
The tests in here have been in a completely non-working state for a very long
time, and it's now getting to a point where it hurts, rather than hinders
development. Nuke them from the tree.
In the future, the useful parts can be brought back easily from history.
Having a single applauncherd process with boosters as plugins is a
flawed idea: most notably, it's not possible to have two boosters with
conflicting libraries, like Qt4 and Qt5.
A much cleaner solution is to turn libapplauncherd into a support
library for boosters, and have each booster run as an independent
process.