Use SIMD for AdapterTrimmer::searchAdapter

[chinwobble]

Adding some tests for searchAdapter so when changes are made we know they are correct.

Profile shows that is one of the bottlenecks. It takes up ~20% of the time.

Flat profile:

Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total           
 time   seconds   seconds    calls  ms/call  ms/call  name    
 48.31      2.43     2.43    31687     0.08     0.08  Stats::statRead(Read*)
 20.08      3.44     1.01    59611     0.02     0.02  AdapterTrimmer::searchAdapter(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, double, int, int, bool, bool)
  8.55      3.87     0.43 42510578     0.00     0.00  edit_distance(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)
  7.75      4.26     0.39  5653164     0.00     0.00  unsigned int edit_distance_map_<1ul>(char const*, unsigned long, char const*, unsigned long)
  7.55      4.64     0.38    94019     0.00     0.00  FastqReader::getLine(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)
  3.38      4.81     0.17        1   170.00   472.84  Evaluator::evalAdapterAndReadNum(Options*, long&)
  1.39      4.88     0.07  3449456     0.00     0.00  unsigned int edit_distance_dp<char>(char const*, unsigned long, char const*, unsigned long)
  1.19      4.94     0.06    14877     0.00     0.00  Filter::passFilter(Read*)

Benchmark shows this code is ~30% faster.

Run on (16 X 3693.05 MHz CPU s)
CPU Caches:
  L1 Data 32 KiB (x8)
  L1 Instruction 64 KiB (x8)
  L2 Unified 512 KiB (x8)
  L3 Unified 8192 KiB (x2)
Load Average: 0.23, 0.39, 0.37
-------------------------------------------------------------------
Benchmark                         Time             CPU   Iterations
-------------------------------------------------------------------
BM_SearchAdapter               1088 ns         1044 ns       668211
BM_SearchAdapterSimd            751 ns          721 ns       981100
BM_SearchAdapterLong           1296 ns         1243 ns       559736
BM_SearchAdapterLongSimd       1001 ns          961 ns       733551

[chinwobble]

make this const so that it can accept an rvalue too.

[chinwobble]

Note that this line has changed.
Previously it was checking it was checking the last nucleotide in the rdata variable.