Updated function declarations in triangulate.c and adssub.c, to address warnings from CRAN Checks page. Incremented version to 1.5-8.

Updated branches/stable-1.5 from ads-1.5-4 and updated NAMESPACE and DESCRIPTION for with new spatstat packages family

Yet another cosmetic change in authors attributes in DESCRIPTION file and deleted unecessary comments in NAMESPACE

Deleted transpose function in utils.R since the C function is absent from utils.c. Deleted it as well from internal.Rd
Deleted utils.c and moved function triangulate to triangulate.c
Renamed C function triangulate into c_triangulate and updated triangulate.R
Added new file init.c to declare C and Fortran functions as recommanded by outputs of tools::package_native_routine_registration_skeleton(".")
Updated NAMESPACE "useDynLib(ads, .registration=TRUE)" as recommanded for R >= 3.4
Updated MD5

In src/*.h cosmetic changes to declare the same way all functions. In fads.R there was a wrong call to ripley_tr_disq_ic instead of coor_tr_disq_ic. Deleted comments en plot.vads.R that were problematic according to devtools:check() function. Updated DESCRIPTION, NAMESPACE and MD5 files