remove the exact integration for condition (abs(yseg(1) -yseg(2))<fuz…

[jsbamboo]

This is to fix the issue #62 to avoid the negative weights in some corner cases.

The current practice is to retain the exact integration algorithm, but never enable it—that is, according to @PeterHjortLauritzen 's instructions mentioned in #62 :

In remamp.F90 change:
    else if (abs(yseg(1) -yseg(2))<fuzzy_width) then
to
    else if (.false.) then