small bug in drawmapscale

还没有人认领这个 Issue。

When using fancy style, the argument ax is not passed to self.plot while plotting the frame and ticks, ex:
#plot bottom line
rets.append(self.plot([x1,x4],[ybottom,ybottom],color=fontcolor)[0])

Thus, part of the map scale may be plotted in a different axes. Ex:

```
import pylab as pl
from mpl_toolkits.basemap import Basemap
m = Basemap(width=3000e3,height=3000e3,resolution='l',
projection='lcc',lat_1=50.,lat_0=47,lon_0=1.)

ax0=pl.axes()
ax1=pl.axes([.6,.5,.15,.15])
m.drawcoastlines(ax=ax0)
lon,lat=-15,47
lon0,lat0=lon,lat
scaleL=400
#pl.axes(ax0) #this will avoid the problem...
o=m.drawmapscale(ax=ax0,lon=lon,lat=lat,lon0=lon0,lat0=lat0,
length=scaleL,barstyle='fancy',fontcolor='r')
```

Start at the Basemap.drawmapscale entry point and inspect the fancy-style frame and tick plotting calls shown in the issue. Reproduce the supplied example with two axes, then verify that every part of the map scale is plotted on the ax0 axes rather than the current axes.

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