Implemented long description for extmods.
A little cleanup
Implemented extmod options print function.
Added extmod_has_* functions.

Used for checking properties of extmod structure without direct field
call.
Rename long and short extmod description fields.

desc      -> desc_short
desc_long -> desc
Uninline some functions.

Also unneeded in public header function was hidden into private
header.
Corrected captions for 'help' and 'version' special extopts.
Fix version extraction for multidigital numbers.
Added global variable 'extmod' pointing to currently executed module
structure.

If no module is executed than value of extmod is 0.
Remove necessety of '--help' option.
Added options substitution in module description.

Function extmod_print_desc now prints module description with
"[[OPTIONS]]" replaced with actual module options usage generated by
extmod_print_opts().
Implemented module extraction from command line arguments.

Now using extmod_extract() function user can extract module from
arguments line. It combines selecting module name and searching for
corresponding module.

Module name is extracted by next rules:
1. if executable name (may be link to executable) is module name - use
that module;
2. otherwise, if first command line argument is module name - use it
and remove it from comman line arguments.

It is recommended to check for correct executable name if this call
returned NULL. Because it would be strange if utility renamed into
nonexisting module name will behave usual way.
Fix crash is some option descriptors don't have long opt name.
Change no-arg parameters argument type to boolean.

This will link library to C99 but there isn't too much sence in caring
for old standard.
Remove allocated string arguments.

Essentially it doesn't do any good, since user always can easily do
strcpy of simple str output if he needs it copied. Moreover, usually
string arguments are only needed to analize.

Also STR_ALLOC type was difficult to remember. will it allocate string
by itself or it should be already allocated'.
Gitignore update.

Format-based rules are added.
Gitignore style update.