add threaded compilation

concerning and closing #465
description of $cur variable fixed
make splint happy
fix (some) race conditions for tests

running the testsuite in multithreaded mode breaks some tests,
especially if run after ```make cleanup```
shredder test thread safety
more thread safe sequniq tests
fix copy paste errors for shredder tests
use apt caching in travis
Merge pull request #467 from Garonenur/travis

add threaded compilation
do not silently pick characters in wildcards
Merge pull request #472 from satta/translate

do not silently pick characters in wildcards
build uses 2 jobs on travis
Merge pull request #474 from Garonenur/travis

build uses 2 jobs on travis
optionally allow non-unique ID output in GFF3 visitor
gtlua: add gt_lua_genome_visitor_push()
add GtGFF3Visitor to speck template namespace

Closes #471.
Merge pull request #476 from satta/beautify_html

Include GFF3 of failing features in speck output
allow to force re-hmmpressing of profiles
make HMMER parser handle PP lines correctly

Addresses #477.
Merge pull request #479 from satta/ltrfixes

Some LTRdigest fixes