API breaks during Tepl 6

There are also ABI breaks not affecting the API, so just re-compiling the program is sufficient in that case.

Tepl 6.0 to Tepl 6.2:

Tepl 6.2 to Tepl 6.4:

Tepl 6.4 to Tepl 6.6:

Tepl 6.6 to Tepl 6.8:

Tepl 6.8 to libgedit-tepl 6.10:

libgedit-tepl 6.10 to libgedit-tepl 6.11: