Fix & muffle sbcl compiler notes and style-warnings

[kilianmh]

74 compiler notes:

• 64 uncertain type (while optimize speed 3)
• 1 complex type assertion
• 1 assignment prevents use of assertion from function type proclamation
• 8 code deletion

2 style-warnings:

• 2 &OPTIONAL and &KEY found in the same lambda list

[ruricolist]

I've merged this with a few tweaks. I'm not seeing any notes or warnings as of SBCL 2.2.7. Thanks!