chore(*): release version 3.4.0

Lean version 3.3.0

chore(*): version 3.2.0

fix(frontends/lean/definition_cmds): set scope_pos_info when checking…

… examples

chore(CMakeLists): make sure we change the version number in a single…

… place

chore(.travis.yml): fix STATIC config

fix(algebra/group_power): change notation suggested by @avigad

fix(frontends/lean): convert paths to cygwin paths in a cygwin binary

Signed-off-by: Leonardo de Moura <[email protected]>