mut_get_ins_long_n: Not inline

Fix this error:
gcc -g -Wall -O2  -o dwgsim src/dwgsim_opt.o src/mut.o src/contigs.o src/regions_bed.o src/mut_txt.o src/mut_bed.o src/mut_vcf.o src/mut_input.o src/dwgsim.o -lm -lz
Undefined symbols for architecture x86_64:
  "_mut_get_ins_long_n", referenced from:
      _dwgsim_core in dwgsim.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
avoid log(0.0)
tell error is opt->dist is too small
Merge pull request #8 from sjackman/patch-1

mut_get_ins_long_n: Not inline
switching sensitivity and specificity in the plots
enforce strandedness
long insertions were not left justified properly
use opt->length[0] + opt->length[1] + opt->is_inner
try to move qual_max 40 to outside
Merge pull request #10 from cielavenir/ciel2

output and error if opt->dist is too small relative to the read length(s)
qual_max: const int -> define
Merge pull request #9 from cielavenir/ciel1

avoid log(0.0)
changing qual_max to QUAL_MAX, to help disambiguate between macro and
variable defines