feat(library/data/category): add category theory

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(library/data/category): add vector

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(emacs/lean-server): scroll debug buffer
feat(emacs/README.md): add instruction for unicode font
feat(emacs/lean-server): add debug-mode, trace-mode
refactor(emacs/lean-server): restructure async queue handling routine
feat(emacs/lean-flycheck): delete flycheck temporaries after check

Close #140
feat(bin/linja): --flycheck option takes a width argument

Close #28
feat(emacs/lean-settings): pass 'pp.width' to lean via linja

Close #28
feat(util): add fuzzy string search procedure
feat(frontends/lean/server): using fuzzy matching
feat(frontends/lean/server): sort fuzzy matches by number of errors

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(shell): allow multiple spaces after -D option

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
chore(emacs/lean-syntax): highlight 'import/section/end/namespace/open' arguments

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(emacs/lean-tags): use the same linja option for tags-gen and flycheck
fix(frontends/lean/inductive_cmd): bugs when declarating inductive datatypes in sections, fixes #141, fixes #142

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/server): ingore keywords and commands in FINDP

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(frontends/lean/server): give preference to prefix matches

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(emacs/lean-server): limit the number of NAY retries

Also, only retry when there is no continuation other than the current
one.
fix(emacs/lean-company): override company--window-width

Override 'company--window-width' to be 0.95 * window-body-width.
This partially solves the problem of issue #137.