Make slices in the table notation "international"

Currently, names of slices can only consist of latin letters without spaces: [\.\w]+

This is somewhat inconvenient, sometimes one needs to make and then aggregate slices with names, say, in cyrillics.

For more details about the proposed slicesRe see [1];
here, other space symbols are also forbidden: \f, \r, \t
(not sure about the first two, this is to avoid confusion with \n, but they can be permitted if needed;
the \t is for another novelty - the \t* part after \:? allows to align slice tables visually in the edit mode, see below).

|name		|value|
|anotherName	|anotherValue|

[1] https://groups.google.com/forum/?hl=en.&fromgroups=#!topic/tiddlywikidev/yFNObuerUw8
Fixed an inconsistency in slicesRE

Previously, in slice name (in "table syntax") \t* was before \4 which is not "correct". I was meant that optional // or '' are closed first, and then optional tabs go. Here, I switched those.
Fixed the issue of and end ":" being included in..

Fixed the issue of and end ":" being included in the slice name:

previously
|sliceName:|sliceValue|
caused the name of the slice to be "sliceName:", now it's "sliceName".
added consist. about white-space around slicenames

Now [in table notation] all white-space around slice-names is stripped off (the first and the last character can't be a white-space symbol \s).

One leading space is allowed before all the wrappers ("//", "''" and "~")
and arbitrary amount of trailing tabs/spaces (after "//", "''" or ":") is as well -
so in the view mode one can have any text-alignment inside cells
and in the edit mode one can make the slices "table" look like a table by aligning "|" with spaces and tabs.
Cut leading/trailing whitespace from slice value

This change is due to the problem from [1].
Some explanations are added in [2].

[1] https://groups.google.com/forum/#!topic/tiddlywiki/9S8R5Sk2niA
[2] https://groups.google.com/forum/#!topic/tiddlywikidev/Z79VDtuW9Uk
Merge pull request #112 from YakovL/patch-1

Make slices in the table notation "international"