.travis.yml: now that gcc is fixed, build on clang, too
LICENSE.md: there is no need for this symlink since the license file is not displayed on github anyways
README.md: This file is not in MD format, so renamed symlink to .TXT
build-mg.sh: improve configurability, script structure (will externalize distro/arch detection next)
- add option for silent installs (APT only for now)
- remove autotools, subversion dependency
- add check for availability of 'git' command
- replace svnversion by git commit output
- add .travis.xml as per http://about.travis-ci.org/docs/user/languages/cpp/
- make git ignore megaglest man page as generated by Linux builds
