makei compile should infer the target using Rules.mk

[TongkunZhang]

Since we have the Rules.mk parser now and allows different names between source and target. We should refer to the Rules.mk files to find out the target name.

[edmundreinhardt]

interesting proposal if the target was not same name as the source

name1.FILE: name2.PF

In the above case, while editing name2.PF, the only way to discover that the target object is name1.FILE is by parsing Rules.mk