[WIP] enhance parser versioning

[masatake]

When releasing, I have to update the NEWS file. One important topic is how parsers are enhanced, with new kinds, roles, fields, and extras (KRFX). We have added and updated the 'ctags-lang-*' man pages mainly to track the KRFX. Updating the man pages only to track them is a boring task. Instead, making ctags itself report new KRFX.

This change adds version members to KRFX definitions.

Various-- list* commands show the version numbers in the VER column:

$ ./ctags --list-kinds-full=Automake
#LETTER NAME      ENABLED REFONLY NROLES MASTER VER DESCRIPTION
D       data      yes     no      0      NONE     0 datum
L       library   yes     no      0      NONE     0 libraries
M       man       yes     no      0      NONE     0 manuals
P       program   yes     no      0      NONE     0 programs
S       script    yes     no      0      NONE     0 scripts
T       ltlibrary yes     no      0      NONE     0 ltlibraries
c       condition yes     yes     1      NONE     0 conditions
d       directory yes     no      6      NONE     0 directories
p       pseudodir no      yes     6      NONE     1 placeholder for EXTRA_, noinst_, ...
s       subdir    yes     no      0      NONE     0 subdirs

--describe-language option was added.

$ ./ctags --describe-language=RpmMacros          
About RpmMacros language
=======================================================
enabled: yes
version: 0.0

Mappings/patterns
-------------------------------------------------------


Mappings/extensions
-------------------------------------------------------


Aliases
-------------------------------------------------------
#ALIAS

Kinds
-------------------------------------------------------
#LETTER NAME  ENABLED REFONLY NROLES MASTER VER DESCRIPTION
m       macro yes     no      0      NONE     0 macros

Roles
-------------------------------------------------------
#KIND(L/N) NAME ENABLED VER DESCRIPTION

Fields
-------------------------------------------------------
#LETTER NAME ENABLED LANGUAGE JSTYPE FIXED OP VER DESCRIPTION

Extras
-------------------------------------------------------
#LETTER NAME ENABLED LANGUAGE FIXED VER DESCRIPTION

Parameters
-------------------------------------------------------
#NAME DESCRIPTION

Sub parsers stacked on this parser
-------------------------------------------------------
#NAME BASEPARSER DIRECTIONS

Implementation specific status
-------------------------------------------------------
allow null tags: no

TODO:

• [ ] implement --list-languages-full
• [ ] update ctags.1.rst
• [ ] add test cases
• [ ] describe versioning in hacking guide
• [ ] ...