Add support for wildcards

The options

AUTO_WILDCARD, MULTI_WILDCARD_CHAR, and SINGLE_WILDCARD_CHAR
are now read from the table and used.

The defaults are:

    AUTO_WILDCARD = TRUE
    MULTI_WILDCARD_CHAR = *
    SINGLE_WILDCARD_CHAR = ?

Now one can use wildcards as in the following example for cangjie5:
“cangjie5.txt” contains:

    sqsf	馬	1000

Now typing something like “s*f” or “s?sf” will match 馬.

If AUTO_WILDCARD = TRUE, a multi wildcard character will always
be appended to the user input, for example typing “s” will
match like “s*”. Until now, ibus-table was always working like that.
Now it is possible to set AUTO_WILDCARD = FALSE to avoid that
automatic final wildcard and get only exact matches. This is
very rarely useful though, take care with that option, in most
cases this should be TRUE!
Add wildcard support also to pinyin mode

The wildcards used are the same as for table mode. I.e. if
the table defines:

    MULTI_WILDCARD_CHAR = *
    SINGLE_WILDCARD_CHAR = ?

the same wildcards are used for pinyin as well.

The AUTO_WILDCARD in the table is ignored for pinyin mode though, it
is always treated as AUTO_WILDCARD = TRUE for pinyin mode, FALSE
does not make any sense for pinyin mode.
Don’t show the prompt characters defined in the table in pinyin mode in the auxiliary text
Merge pull request #38 from mike-fabian/add-support-for-wildcards

Add support for wildcards