gnuplot: added bmargin for plots that had rotated x labels cut off.

doc/TODO.txt

 	- git-log --pretty=format:"%at %an" |grep -C3 unknown
 	- git-rev-list (for number of files in each revision) says "Warning: failed to parse line "<unknown> 17741"
 
-[Bugs]
-- Graphs: vertical x labels get cut off
-
 [Unsorted]
 - clean up after running gnuplot (option to keep .dat files around?)
 - show raw data in some way (the tables used currently aren't very nice)

gitstats

 set timefmt "%Y-%m"
 set format x "%Y-%m"
 set xtics rotate by 90 15768000
+set bmargin 5
 set ylabel "Commits"
 plot 'commits_by_year_month.dat' using 1:2:(0.5) w boxes fs solid
 """)
 set format x "%Y-%m-%d"
 set ylabel "Files"
 set xtics rotate by 90
+set bmargin 6
 plot 'files_by_date.dat' using 1:2 smooth csplines
 """)
 		f.close()
 set format x "%Y-%m-%d"
 set ylabel "Lines"
 set xtics rotate by 90
+set bmargin 6
 plot 'lines_of_code.dat' using 1:2 w lines
 """)
 		f.close()