Fix out of source builds

Fixes #1018
win32: Fixed build break due to 7a4a024
Replace some unsafe usage of strncpy

Ensure everything is null terminated
Increase max len of chiper names

For example ECDHE-ECRSA-AES256-GCM-SHA384
Fix missing header

And just use g_snprintf() while at it..
Fix attempting to toggle visibility when tray disabled
Take two at fixing out of source builds
travis: Add clang & CPUs & fast_finish

HexChat seems to compile fine with clang so why to not test it too.
-j$(nproc) seems to work with HexChat and fast-finish marks build as
failed if one job fails.

Fast finish won't stop jobs that aren't finished at the time of failure.

Closes #1147