hgweb: Keep session variables (currently only style) in HTML forms, too.
Adjusted default and gitweb template for this.
default = 'changelog'
header = header.tmpl
changelog = changelog.tmpl
changelogentry = changelogentry.tmpl
filelog = filelog.tmpl
filelogentry = filelogentry.tmpl
tags = tags.tmpl
tagentry = tagentry.tmpl