spice plot resolution - sinusoid does not look continuous
The syntax is 

.TRAN TSTEP TSTOP [ [ TSTART ] TMAX ] [ UIC ]

Changing 


  tran 1.0ns 100ms


To


  tran 1us 100ms 0 1us


has solved the issue. In the user guide, note that the TSTEP doesn't exclusively control the step size.  TMAX must also be set. The boldface text explains why.


  
  TSTEP is the printing or plotting increment for line-printer output. For use with the post-processor, TSTEP is the suggested computing increment. 
  TSTOP is the final time
  TSTART is the initial time. If TSTART is omitted, it is assumed to be zero. The transient analysis always begins at time zero. In the interval , the circuit is analyzed (to reach a steady state), but no outputs are stored. In the interval , the circuit is analyzed and outputs are stored. 
  TMAX is the maximum step-size that SPICE uses; for default, the program chooses either TSTEP or (TSTOP-TSTART)/50.0, whichever is larger. TMAX is useful when one wishes to guarantee a computing interval which is smaller than the printer increment, TSTEP.
  
  http://www.macspice.com/ug/sec4.html#s4.3.9