created poppler method signagures changes tip

Author: stephengaito

docs/TipsAndTricks/PopplerMethodSignaturesChange.md

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+# When Poppler method signatures change...
+
+When Poppler method signatures change, use the command:
+
+    reset; grep -sinr <<name of method>>
+
+in a local copy of the poppler source code.
+
+This should provide examples of what changes the poppler
+programmers made to their own code to adapt to their own
+method signature changes.
+
+In this situation, it can be helpful to have *two* local 
+copies of the poppler source code, one copy at the last
+version for which pdf2htmlEX is know to work, and on copy
+of poppler at the new version. Once you have identified
+examples of the uses of the new method signatures, you
+can diff the poppler code between the two versions to
+see *how* the poppler programmers made the changes.