Raise minimal version of prompt_toolkit to 0.53.

It has a backward incompatible change to rename the get_input() function
to prompt(). For now it's still supported, but it's better to anticipate
the removal of get_prompt() in the (near?) future.

setup.py

@@ -39,7 +39,7 @@ setup(
     ] + [p for p, cond in conditional_dependencies.items() if cond],
     extras_require = {
         'ical': ['icalendar'],
-        'prompt-toolkit': ['prompt-toolkit >= 0.47'],
+        'prompt-toolkit': ['prompt-toolkit >= 0.53'],
         'edit-cmd-tests': ['mock'],
     },
     entry_points= {

topydo/cli/Prompt.py

@@ -21,7 +21,7 @@ import sys
 
 from topydo.cli.CLIApplicationBase import CLIApplicationBase, error, usage
 from topydo.cli.TopydoCompleter import TopydoCompleter
-from prompt_toolkit.shortcuts import get_input
+from prompt_toolkit.shortcuts import prompt
 from prompt_toolkit.history import InMemoryHistory
 
 from topydo.lib.Config import config, ConfigError
@@ -90,7 +90,7 @@ class PromptApplication(CLIApplicationBase):
             self._load_file()
 
             try:
-                user_input = get_input(u'topydo> ', history=history,
+                user_input = prompt(u'topydo> ', history=history,
                                        completer=self.completer,
                                        complete_while_typing=False).split()
             except (EOFError, KeyboardInterrupt):

topydo/cli/TopydoCompleter.py

@@ -15,7 +15,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 """
-This module provides a completer class that can be used by get_input provided
+This module provides a completer class that can be used by the prompt provided
 by the prompt toolkit.
 """