do not pass --with-intree-gmp to configure when system gmp is used

[skip ci]

[skip ci]

See #183.

fix "dirs" to "dir" for gmp and iconv libraries

Fix #176.

fix handling of FFI library configure params

Conflicts:
	cfg/system.config.in

Fix #124.

Fix #181.

See #181. [skip ci]

See #100.

[skip ci]

See #176.

[skip ci]

See #174.

See #174.

[skip ci]

See #167.

See #167.

Fix #167.

See #167.

See #173.

[skip ci]

advanced render box, fix #134 [skip ci]

# Conflicts:
#	src/Base.hs