add a few system functions to the 2450 driver

[liangosc]

The following methods are added:

def abort(self) -> None:
    """
    This command stops all trigger model commands on the instrument.
    """
    self.write(":ABORt")

def initiate(self) -> None:
    """
    This command starts the trigger model.
    """
    self.write(":INITiate")

def wait(self) -> None:
    """
    This command postpones the execution of subsequent commands until all
    previous overlapped commands are finished.
    """
    self.write("*WAI")

def clear_event_register(self) -> None:
    """
    This function clears event registers.
    """
    self.write(":STATus:CLEar")

def clear_event_log(self) -> None:
    """
    This command clears the event log.
    """
    self.write(":SYSTem:CLEar")

@sohailc

[codecov]

Codecov Report

Merging #2052 into master will decrease coverage by 0.00%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master    #2052      +/-   ##
==========================================
- Coverage   71.43%   71.42%   -0.01%     
==========================================
  Files         149      150       +1     
  Lines       20063    20076      +13     
==========================================
+ Hits        14331    14339       +8     
- Misses       5732     5737       +5