fix detection for CXX=clang
travis: for now, clang build result should not impact overall build result
hopefully this gives us just two travis builds (not 4)
build-mg.sh: no more warning when clang is not installed [ci skip]
travis: don't apt-get upgrade build node
Windows: delete Release\*.tlog before building
No prompt for file removal
Also support -DCMAKE_BUILD_TYPE=None which is used by Debian

Fixes: https://bugs.debian.org/739068
Merge pull request #9 from pabs3/develop

Also support -DCMAKE_BUILD_TYPE=None which is used by Debian
optional start-ep tag implemented
fixed an unimported copy&paste tag :) had no influence afaik but still
better like this
Merge pull request #14 from FreshDumbledore/develop

Start EP can be set
testing version of multiple projectiles
multishot with more than one attack particle system
use  a bool instead of a (unused) pointer.
multi projectiles with different timings and particle systems
Start ep now an argument of max-ep

Syntax is `<max-ep value="500" start-value="250" />`
Implemented start percentage for EP

Note that start-value and start-percentage (both are attributes of the
max-ep tag) are mutually exclusive. If they both exist, then
start-percentage is used.
Error checking now active for start-ep

You can no longer have both start-value and start-percentage.
multishot with multi sounds and possible camerashake on projectile impact. 

Still work in progress!