Add option to ignore symlinks completely

[blenk92]

When analyzing a complete rootfs (which might not be the rootfs of the analyzing system) symlink within that rootfs might be broken. In particular absolute symlinks. However, if by chance such a symlink currently points to a valid binary in your system, this binary pointed to is analyzed. This commit adds the possibility to ignore symlinks to files (symlinks to dirs are already ignored by default). This allows to solve the issue described above, and if the whole rootfs is analyzed there shouldn't be a loss of information (because all the binaries will be analyzed anyway). Additionally, this also saves some time when performing the analysis.