Refactor j2k_read_ppm_v3 function

[gcode-importer]

Originally reported on Google Code with ID 470

While fixing issue 392, it appeared that function j2k_read_ppm_v3 should be refactored
(and renamed) in the following way : 

while reading the MH (in opj_j2k_read_header_procedure), concatenate all Nppm and corresponding
Ippm's and parse them all at once, once getting out of the while loop of the MH processing.
This would allow the processing of ppm data in the right order (if by any chance Zppm
are not in increasing order) and would avoid the need of adding a parameter to all
marker handlers to fix the ASan error with x64 (see issue 392).

Sanity checks at
https://code.google.com/p/openjpeg/source/browse/trunk/src/lib/openjp2/j2k.c?r=2963#3600
https://code.google.com/p/openjpeg/source/browse/trunk/src/lib/openjp2/j2k.c?r=2963#3644
might need to be removed too.

Reported by detonin on 2015-01-15 17:39:06

[mayeut]

j2k_read_ppt shall probably be refactored as well