Remove old config migration

Fixes #1194
configure: Fix checking for perl

Closes #1196
Fixes #1197
Warning cleanup

- ignoring const
- declarations after statements
- some C files didnt include own headers (risking them getting out of sync)

Closes #1064
ssl: Don't use global openssl context

Fixes #789
ssl: Use more secure options

This disables ssl 2/3
ssl: Validate hostnames

Closes #524
Fix possible crash in SASL Blowfish mech
Bump updater version to 2.10.2
Add alerts for invalid ssl certs

This patch was originally provided by dila in #xchat
but modified heavily since.

It will show an alert on invalid certs to add
temp or permanent exceptions per server.