fix font file verification (thanks, Kim!)

the cached lookup did not load the database when verifying
the presence of hashed files.

addresses: https://github.com/lualatex/luaotfload/issues/100
document kpse: and my: lookups
[doc] add note concerning unreliability of font names
add --inspect and --warnings flags to luaotfload-tool
add ascii heading formatter to luaotfload-tool
printer for the names table
add font metadata printer
[doc] describe -I and -w in manpage
add gsub/gpos feature list to --inspect
add counters to info output sections for better legibility