fix(frontends/lean/scanner): decode utf8

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
refactor(kernel/pos_info_provider): get_pos_info return none if position is not available

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/elaborator): add flyinfo for placeholders

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(frontends/lean/elaborator): provide type information for expressions using '@' operator, and strict function applications

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(frontends/lean): flyinfo for identifiers defined in sections

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
chore(util/sexpr/options): typos

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/standard): add markdown documentation
feat(library/standard/logic/axioms): add import default
feat(library/standard/data/nat): port most recent nat to lean 0.2
refactor(library/standard/data/nat): stylistic changes
fix(library/coercion): spurious 'replacing coercion', fixes #22

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean): display warning message when importing file that uses 'sorry'

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/scanner): allow letter-like unicode characters and sub/super-scripts in identifiers

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>