merge: Re-sort resources for better documents

 * doc/neomuttrc.man.head: Sort commands
 * doc/neomuttrc.man.head: Add and fix command definitions
 * doc/neomuttrc.man.head: Small tidying
 * doc/neomuttrc.man.{head,tail}: Catch up overlooked parts
 * doc/neomutt.man: Keep man-pages consistent
 * Provide timestamp expansion and fix man pages date
 * Minor tidying of inner/trailing whitespace
 * auto.def: Use nested evaluations
 * auto.def: Simplify PACKAGE_VERSION fallback case
 * Simplify generation of man date
 * Fix man substitutions
 * Remove useless defines
 * auto.def: Refine PACKAGE_DATE comment
 * Correct */mime.types lookup order in comments
 * doc/manual.xml.head: Adapt definitions of commands
 * doc/manual.xml.head: Remove logical NOT operator
 * doc/manual.xml.head: Sort/Group command definitions
 * Rewrite manual page neomutt(1)
 * Rewrite manual page neomuttrc(5)
 * doc/manual.xml.head: Complete table command line options
 * Document command line option -l
 * main.c: Rewrite `neomutt -h` output
 * Adopt formatting and finalise syntax sanitising