.gitignore: add autotools' `compile`

autoconf now[1] generates a symbolic link named compile (that
targets /usr/share/automake-1.14/compile) in the root of the
repository when running, so let's include it in .gitignore to
achieve a clean `git status` after compiling (or avoid breaking
the build via `git clean -fd`).

[1] This started happening to me since the usage of Ubuntu14.04,
which brings autoconf 2.69, and prints:

configure.ac:16: installing './compile'

(Having AC_PROG_LIBTOOL in that line)
Merge pull request #185 from knocte/gitignore
Frontend-GNOME: any server support

Servers were always reconstructed in the UI, thus settings that are read from
the config backend but not exposed in the UI were lost. Instead the ServerModel
object is now reused, filled with the known UI values and passed as is to the
engine.
Engine: re-apply MessageBuilderSettings on config changes

If highlight words were changed, the old words were still highlighted and not
the new ones.