converts binary to hex representation.

Example:

data:
<<1,18,35,52,69>> (which is equal to <<16#01,16#12,16#23,16#34,16#45>>)

hex representation:
<<"0112233445">>

call:
bin_md:to_bin_text(<<1,18,35,52,69>>) -> <<"0112233445">>

Works little faster than ssl_debug.erl because prints hex data only
without text. Sometimes the hex hash is the only thing you need.

The sd2 module used in tests is just a copy of
ssl_debug.erl from OTP compiled with 'export_all'.
The sd2b module used in tests is a copy of
ssl_debug.erl with asciify/1 replaced with a stub.

You can use, reuse and abuse this code.

Time:

1)
  for sd2 (hex_asc/0 calls both hexify/1 and asciify/1):
  cmp_hex:batch(100000) -> {100000,3.018612,6.330802}

  to_bin_text - 3 s
  hex_asc (from ssl_debug) - 6.3 s

2)
  for sd2b (hex_asc/0 calls only hexify/1):
  cmp_hex:batch(100000) -> {100000,2.998139,5.421503}

  to_bin_text - 3 s
  hex_asc (from ssl_debug) - 5.4 s