Log message:
python/wheel.mk: simplify a lot, and switch to 'installer' for installation

This follows the recommended bootstrap method (flit_core, build, installer).

However, installer installs different files than pip, so update PLISTs
for all packages using wheel.mk and bump their PKGREVISIONs.

Log message:
py-tlv8: add missing TOOL_DEPENDS

Not for Python 2. Shorten DESCR.

Log message:
py-tlv8: import as devel/py-tlv8 version 0.10.0

Type-Length-Value8 (TLV8) for python

Type-Length-Value (TLV) are used to encode arbitrary data.
In this case the type and length are represented by 1 byte each.
Hence the name TLV8.

A TLV8 entry consists of the following parts:
    * the type: this 8 bit field denotes the type of information
      that is represented by the data.
    * the length: this 8 bit field denotes the length of the data
      (this does not include the 2 bytes for type and length.
      For data longer than 255 bytes, there is a defined procedure available.
    * the value: these length bytes represent the value of this TLV.
      The different types of data is represented differently:
        * bytes: this is raw binary data and will be used as is, no further
          interpretation takes place
        * tlv8: this is a specialized case of bytes values. Using this instead
          of pure bytes enables nesting of data and creating a hierarchy.
        * integer: integers are stored in little-endian byte order and are
          encoded with the minimal number of bytes possible (1, 2, 4 or 8)
        * float: floats are stored as little-endian ieee754 numbers
        * string: strings are always UTF-8 encoded and do not contain the
          terminating NULL byte

TLV8 entries whose content is longer than 255 bytes are split up into fragments.
The type is repeated is repeated in each fragment, only the last fragment may
contain less than 255 bytes. Fragments of one TLV8 entry must be continuous.

Multiple TLV8 entries can be combined to create larger structures.
Entries of different types can placed one after another.
Entries of the same type must be separated by a TLV8 entry of a different
type (and probably zero length).

TLV8 entries of unknown or unwanted type are to be silently ignored.