If release contains many commits and/or those commits contain many
changed files, the command line could grow past OS limit.  Using stdin
avoids this.

Not just on update but also on creation.

Project-related, then codebase-related, then (binary)-package-related.

If sources are built using `dist`, `rpmstuff` or `debstuff`, current
version of MKit does not actually require git--all that is necessary
should be cached in the tarball anyway.

Regarding coreutils, they are part of essential set on most
distributions; on those, one should actually refrain from specifying
them.

Overview of changes:

 *  Added data-sampler pseudo-target

    To help developers see what tokens are available, this pseudo-target
    just prints list of tokens and their values, for built-in tokens as
    well as for user-defined.

 *  Removed obsolete build_manpages target and 'markdown' type

    These were not compatible with current design od MKit and will
    be better off re-implemented as plugins.

 *  Items in changelog template are now delimited by empty line

    Just for convenience when formatting and extending.

 *  ini() can now list all sections from mkit.ini ('ini lssect')

 *  Refactored internal functions with double underscore

 *  Updated own meta-data

 *  Fixed small typos in comments and docstrings

 *  Quoted $MKIT_DIR properly in mkit.mk

 *  Updated own dogfood

Single underscore will be used for not-so-hidden names.

They're based on obsolete mkit.ini structure and is not used in any known
project.  That said, at least build_manpages will be added in future,
most probably in form of plugin, once plugin structure is figured out.
(Stay tuned, but don't hold your breath!)

Found by running ShellCheck on .mk file ... by accident!

The changelog is intended to be edited, but it's more convenient this
way (especially if you're like me, using Vim and '{' and '}' as major
means of moving around.

...if we can't fix the FIXME itself.

Overview of changes:

 *  build target will now leave file .mkit/semver file

    Build tools can read this to easily find out version.

 *  semver() caches its output now

 *  Refactored common operations in .mkit

 *  Removed old unnecessary check

 *  Solved or muted last few ShellCheck issues

To make it easier for build tools to read full version information.

A bit convoluted check that cannot fail, since everything now relies on
var.sh being imported, which is guarranteed to set $MKIT_LOCAL to a
non-empty value.

Overview of changes:

 *  mkit/stub: Removed `[roots]` reference from `[tokens]` example

    Using '[roots]' as reference can have unpredictable results since it
    silently depends on DESTDIR, which is only available at install
    time.

    Next breaking release (v0.1.0, but could be earlier as we are still
    in 0.0.z space) should rename 'roots' to 'ROOTS' to reflect its
    volatile nature (similar to ENV).

 *  mkit/stub: LICENSE.md won't be mentioned in headers if not asked

 *  mkit/stub: PREFIX is set to /usr in packaging templates

 *  mkit/stub: Added notes about file paths in packaging templates

 *  mkit/stub: Fixed bug when empty license name would be accepted

 *  mkit/stub: Fixed double deploy of template.spec

 *  mkit/make: Having relsrc same as reldst is now tolerated (albeit useless)

 *  mkit/make: 'release' and 'vbump' can now be reached directly (without GNU Make)

 *  mkit/make: Added -V option to mkit/make script

 *  Code maintenance

Defining same reldst as relsrc is useless, but does not harm, so we can
let it slip through.

Use of `[roots]` in `[tokens]` is tricky, because final value of a
`[roots:foo]` will "silently" depend on DESTDIR, while DESTDIR is
only known during install time.  On the other hand, `[tokens]` are used only
during build time.

In other words, YOU CANNOT RELY on the value of keys in `[roots]` to be
consistent.  For example, consider root:

    [roots]
        foo = /bar
        qux = [ENV:PREFIX]:/quux

`[roots:foo]` will be '/bar' at build time, but "$DESTDIR/bar" at
install time, and `[roots:qux]` will be "$PREFIX/quux" at build time,
but "$DESTDIR/$PREFIX/quux" at install time.

Just about only case when you might want to use it is mentioning it in
a document, when you want the value to be rather "standard" than
"correct", while you still want to respect PREFIX.

So let's not lead new users directly into that rabbit hole.

Usage of GNU Make really is just a sugar, so we should enable all
targets also for direct mkit/make invocation.

We have no tests so TFKit is useless here.

Overview of changes:

 *  Fixed version directive lookup

    mkit.ini would be refused if version directive was at the end of the
    file, while first and last 3 lines is what was supposed to work.

 *  Fixed license argument check

    stub script would ignore license argument due to argument validation
    error caused by refactoring.

 *  Fixed bad grep advice in MKIT_STUB_README.md

 *  Updated own dogfood

I don't know how I came up with that pipe but it's certainly wrong.

Earlier I replaced all checks on $License valiue when I should have
replaced all *but this one*.