str_repr.hh: Switch to decimal represenation of floating types

Instead of hexadecimal, use (exact) decimal representation of floating
points to achieve compatibility with other graphml readers.

This fixes issue #570.
6 jobs for master in 128 minutes and 44 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #3961
amd64
job_clang_amd64

failed #3965
amd64
job_clang_amd64_nosh

failed #3963
amd64
job_clang_py2_amd64

failed #3960
amd64
job_gcc_amd64

failed #3964
amd64
job_gcc_amd64_nosh

02:08:15

failed #3962
amd64
job_gcc_py2_amd64

02:08:43

 
Name Stage Failure
failed
job_gcc_py2_amd64 Test
make[4]: Leaving directory '/var/lib/gitlab-runner/builds/c098b1de/7/count0/graph-tool/src/graph/inference'
make[3]: *** [Makefile:809: all-recursive] Error 1
make[3]: Leaving directory '/var/lib/gitlab-runner/builds/c098b1de/7/count0/graph-tool/src/graph'
make[2]: *** [Makefile:422: all-recursive] Error 1
make[2]: Leaving directory '/var/lib/gitlab-runner/builds/c098b1de/7/count0/graph-tool/src'
make[1]: *** [Makefile:594: all-recursive] Error 1
make[1]: Leaving directory '/var/lib/gitlab-runner/builds/c098b1de/7/count0/graph-tool'
make: *** [Makefile:481: all] Error 2
ERROR: Job failed: exit status 1
failed
job_gcc_amd64_nosh Test
make[4]: Leaving directory '/var/lib/gitlab-runner/builds/c098b1de/6/count0/graph-tool/src/graph/inference'
make[3]: *** [Makefile:809: all-recursive] Error 1
make[3]: Leaving directory '/var/lib/gitlab-runner/builds/c098b1de/6/count0/graph-tool/src/graph'
make[2]: *** [Makefile:422: all-recursive] Error 1
make[2]: Leaving directory '/var/lib/gitlab-runner/builds/c098b1de/6/count0/graph-tool/src'
make[1]: *** [Makefile:594: all-recursive] Error 1
make[1]: Leaving directory '/var/lib/gitlab-runner/builds/c098b1de/6/count0/graph-tool'
make: *** [Makefile:481: all] Error 2
ERROR: Job failed: exit status 1
failed
job_clang_amd64_nosh Test There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log
failed
job_clang_py2_amd64 Test There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log
failed
job_clang_amd64 Test There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log
failed
job_gcc_amd64 Test There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log