Merge branch 'nd/log-graph-configurable-colors'

Some people feel the default set of colors used by "git log --graph" rather limiting. A mechanism to customize the set of colors has been introduced. * nd/log-graph-configurable-colors: document behavior of empty color name color_parse_mem: allow empty color spec log --graph: customize the graph lines with config log.graphColors color.c: trim leading spaces in color_parse_mem() color.c: fix color_parse_mem() with value_len == 0