E3-1214: Fix usage of string functions

This MR carries many changes, but the major one s a rework of the linked list. This change removes the use of strlen in many places of the code, and collect them in a single function were we use strnlen. This also simplify the access to content fields, now we have direct pointers to them :). Combining the more comprehensible structure with the separation in other files we got way better readability.

The strchr calls on the code are safe actually as they are all on literals.