disable vimIM
vimgdb: don't change vim settings when start gdb
check gdb support before setting
sync NERDTree when open new files, change zt/zb behavior
remove trailing space at end of line
don't sync nerdtree when in __Tag__Lists__ buffer
ignore special buffers when sync nerdtree
only sync nerdtree when opening interesting files and some other configs
startify: using relative path and donot change to dir when opening files