add trn_grid_set_row function

this function is used to shorten the fnc trn_grid_fill
this solves the issue #14
Merge pull request #24 from raoufhamouda/subfunction_in_trn_grid_fill

add trn_grid_set_row function
Fix issue 15, extract code into is_row_equal
Merge pull request #25 from tibaugasc/issue15

Fix issue 15, extract code into is_row_equal
KWstyle: check only line length

This solve issue #26.
add function trn_grid_fill_row
merge with other group