Fix broken truncate filters (#138)
Fix broken truncate filters (#138)

```erlang
erlydtl_tests: all_defs_test_ (filters: |truncatewords:0)...*failed*
in function erlydtl_eunit_testrunner:'-run_render/1-fun-0-'/2 (test/erlydtl_eunit_testrunner.erl, line 73)
**error:{assertEqual_failed,[{module,erlydtl_eunit_testrunner},
                     {line,73},
                     {expression,"B"},
                     {expected,<<" ...">>},
                     {value,<<>>}]}
```

oxpa/erlydtl,erlydtl/erlydtl,alexr/erlydtl,erlydtl/erlydtl,A40in/erlydtl,wrw/erlydtl,chaptastic/erlydtl,A40in/erlydtl,campanja-forks/erlydtl,truqu/erlydtl,aerosol/erlydtl,kivra/erlydtl,truqu/erlydtl,huangered/erlydtl,chaptastic/erlydtl,oxpa/erlydtl,quasiconvex/erlydtl,campanja-forks/erlydtl,wrw/erlydtl,truqu/erlydtl,huangered/erlydtl,quasiconvex/erlydtl,kivra/erlydtl,wrw/erlydtl,project-fifo/erlydtl,alexr/erlydtl,aerosol/erlydtl,alexr/erlydtl,campanja-forks/erlydtl,chaptastic/erlydtl,huangered/erlydtl,project-fifo/erlydtl,oxpa/erlydtl,project-fifo/erlydtl,erlydtl/erlydtl,kivra/erlydtl,aerosol/erlydtl,A40in/erlydtl,quasiconvex/erlydtl