[#3276] Trying to further clarify the session storage directory details
improve the serialization of custom user models

(cherry picked from commit 7b34eabe4b506c3e49e4dedbefee66c1612bb83d)
[#3307] Adding an additional note about deserialization issues

(cherry picked from commit 7325ec5044c0339275a9700e767d88707116f79d)
[#3307] Fix thanks to @xabbuh

(cherry picked from commit 38612bc190ab2f97f2fbd3f3bc18a591df153cbe)
Clarifying some details on serialize/unserialize and making it consistent with changes we recently made

(cherry picked from commit f285c5a572ee88e94a9314e152a5075243811d49)

Conflicts:
	cookbook/security/entity_provider.rst
Changed sha1 into bcrypt
[#3356] Fixing ticks that don't work inside a bold and removing extra details in intro area that aren't necessary (you'll need to read the cookbook entry for more details anyways)
[#3356] Changing to use the bcrypt algorithm

Also removing one example (now possible with using bcrypt from the beginning) and related tweaks.
[#3356] Moving serialize and Equatable logic further down for clarity
[#3356] Clarifying when you need a salt

Also filling in other details related to using BCrypt
add warning for inifile loader
Add host config to the security documentation
add host to the config page
line break
fix indentation so that the text is rendered properly
[Reference][Form Types] Update "radio" form type
Fix parent type doc reference
Update&Outsource "value" option & update references
[Reference][Form Types] Add missing (but existing) form options to "form"
type
address comments, even the Boolean one