Fix several typos.

Author: jonathanslenders

ptterm/backends/darwin.py

@@ -40,7 +40,7 @@ def _init():
             LIBC = cdll.LoadLibrary("libc.dylib")
         except OSError:
             # On OS X El Capitan, the above doesn't work for some reason and we
-            # have to explicitely mention the path.
+            # have to explicitly mention the path.
             # See: https://github.com/ffi/ffi/issues/461
             LIBC = cdll.LoadLibrary("/usr/lib/libc.dylib")
 
@@ -73,7 +73,7 @@ def get_proc_info(pid):
 
 def get_proc_name(pid):
     """
-    Use sysctl to retrive process name.
+    Use sysctl to retrieve process name.
     """
     proc_kinfo = get_proc_info(pid)
     if not proc_kinfo:

ptterm/terminal.py

@@ -123,7 +123,7 @@ def get_line(number: int) -> StyleAndTextTuples:
         if data_buffer:
             line_count = (
                 max(data_buffer) + 1
-            )  # TODO: substract all empty lines from the beginning. (If we need to. Not sure.)
+            )  # TODO: subtract all empty lines from the beginning. (If we need to. Not sure.)
         else:
             line_count = 1
 
@@ -261,7 +261,7 @@ class Terminal:
     """
     Terminal widget for use in a prompt_toolkit layout.
 
-    :param commmand: List of command line arguments.
+    :param command: List of command line arguments.
         For instance: `['python', '-c', 'print("test")']`
     :param before_exec_func: Function which is called in the child process,
         right before calling `exec`. Useful for instance for changing the