Fix new tabs overriding default syntax rules

Calling `syntax on` will override existing syntax rules with default
ones. This ends up adding a bunch of syntax rules that users have
disabled.

See `:help syntax` for this snippet:

    The ":syntax enable" command will keep your current color settings. This
    allows using ":highlight" commands to set your preferred colors before or
    after using this command.  If you want Vim to overrule your settings with
    the defaults, use: `:syntax on`

Calling `:syntax enable` doesn't appear to work either. It does the same thing
as `:syntax on`. So the solution implemented here is to conditionally set the
filetype and syntax rules when they aren't already set.
added :Pyedit vim command

    :Pyedit [++opt] [+cmd] module

    module is a python module, there is a completion for them as well.
    [opt] and [cmd] are like for the :edit command.
g:jedi#quickfix_window_height

    This commit adds an option g:jedi#quickfix_window_height, with the
    default value 10 (as this is the default value for :copen)
add doc/tags to gitignore
ctrl space cycles now through results, when used multiple times, fixes #118
Merge branch 'master' of git://github.com/coot/jedi-vim into pyedit
improve indentation of #117
Merge branch 'bugfix-newtab-syntax' of git://github.com/artnez/jedi-vim into newtab
use is_keyword instead of hack
Merge branch 'dev' into newtab
renamed Pyedit to Pyimport, refs #117