Log Message:
Update mlterm to 3.7.2.

XXX: mlterm-con is not handled yet

Changes noted in doc/en/ReleaseNote:

ver 3.7.2
* Add mlterm-con which is a console version of mlterm (like GNU Screen) and which
  works on various terminal emulators. (see doc/en/README.console)
* Add "console_encoding" / --ckm option which specifies a character \ 
encoding of
  the console where mlterm-con works.
* Add "default_cell_size" / --csz option for mlterm-con.
* Add "console_sixel_colors" / --csc option for mlterm-con.
* Add "primary_da" / --da1 and "secondary_da" / --da2 options.
* Support DECRQSS partially.
* Support wheel mouse on MacOSX/Cocoa. (Thanks to @nyarla)
  (Merge a patch at http://the.nyarla.net/entry/2016/06/03/195013)
* Bug fixes:
  Fix misalignment of the position of characters in drawing them with the use
  of complementary loaded fonts on cairo.