Ltermio

* Rename make_color() to rgb().
+ Add a new function reset_textattr() to restore attributes of text.

* Re-encode mouse events into high 13 bits of the 32 bits integer.
+ Add supporting of mouse buttons 6 and 7.
* Modify the descriptions about MouseEvent in comments and docstrings.
+ Add a new enum TextAttr to define attributes like BOLD, ITALIC, etc.
+ Add new funcs set_textattr() textattr_seq() to set text attributes.
+ Add a new enum CursorShape to define cursor shapes.
+ Add new func set_cursor_shape() to change cursor shape.

* Make MouseEvent as a global enum.
+ Add aliases for buttons, B1 -> B_LEFT, B2 -> B_MIDDLE, B3->RIGHT.
* Modify some wrong descriptions in docstrings.

* Rename parameterized decorator appentry() to appentry_args().
+ Add a new non-parameter decorator appentry().

* Change the modifier values that defined in Key, to prevent conflicts.
* Prefix 'r' for all docstrings of the package to assure WYSWYG.
+ Add more docstrings for mouse module.
+ Add contents of module docstrings to README.md.

* Optimize the implement of termouse module.
* Modified the import pattern in __init__.py.
* Change some descriptions of comments.