Split Header into Header and HeaderFormat
Split Header into Header and HeaderFormat

Header contains all of the trait-object unsafe methods
including the name of the header and parsing. HeaderFormat
contains fmt_header, which is the only trait-object safe
method.

pyfisch/hyper,mfeckie/hyper,golddranks/hyper,peterhj/hyper,retep998/hyper,tshepang/hyper,nstoddard/hyper,golddranks/hyper,nickgonzales/hyper,hyperium/hyper,hannobraun/hyper,sfackler/hyper,yazaddaruvala/hyper,steveklabnik/hyper,huonw/hyper,Twey/hyper,jmmaranan/hyper,yazaddaruvala/hyper,tempbottle/hyper,Keats/hyper,nickgonzales/hyper,Keats/hyper,ianks/hyper,Ryman/hyper,Manishearth/hyper,yangxingpping/hyper,PeterReid/hyper,markuskobler/hyper,giftcards/hyper,TimNN/hyper,tshepang/hyper,frewsxcv/hyper,bonifaido/hyper,youprofit/hyper,golddranks/hyper,erickt/hyper,fengsp/hyper,clatour/hyper,tshepang/hyper,mitsuhiko/hyper,markuskobler/hyper,achanda/hyper,nickgonzales/hyper,reem/hyper,hyperium/hyper,mlalic/hyper,markuskobler/hyper,softprops/hyper,nstoddard/hyper,hannobraun/hyper,manuel-woelker/hyper,servo/hyper,mlalic/hyper,bheesham/hyper,hyperium/hyper,pcwalton/hyper,mikedilger/hyper,mre/hyper,Twey/hyper,lame-nickname/hyper,rschulman/hyper,fuchsnj/hyper,Twey/hyper,fhahn/hyper,mneumann/hyper,hannobraun/hyper,Keats/hyper