Sync

When some changes happen in the official SQLite repository, they can be applied locally:

• $SQLITE/tool/lemon.c => $RLEMON/third_party/lemon.c
• $SQLITE/tool/lempar.c => $RLEMON/third_party/lempar.rs
• $SQLITE/tool/mkkeywordhash.c => $RLEMON/src/dialect/mod.rs
• $SQLITE/src/tokenize.c => $RLEMON/src/lexer/sql/mod.rs
• $SQLITE/src/parse.y => $RLEMON/src/parser/parse.y (and $RLEMON/src/dialect/token.rs, $RLEMON/src/dialect/mod.rs)