Fix some issues reported by lintian

Fix some issues reported by lintian

• Trim trailing whitespace. (trailing-whitespace)
• Use secure URI in Homepage field. (homepage-field-uses-insecure-uri)
• Use canonical URL in Vcs-Browser. (vcs-field-not-canonical)
• Update standards version to 4.6.1, no changes needed. (out-of-date-standards-version)
• Trim trailing whitespace. (trailing-whitespace)
• Use secure URI in Homepage field. (homepage-field-uses-insecure-uri)
• Use canonical URL in Vcs-Browser. (vcs-field-not-canonical)
• Update standards version to 4.6.1, no changes needed. (out-of-date-standards-version)

This merge proposal was created by the Janitor bot, and it will automatically rebase or close this proposal as appropriate when the target branch changes. Any comments you leave here will be read by the Janitor's maintainers.

Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/ipe/bf41fad1-a8cb-42d7-b344-c3d9709f9b19.

Debdiff

These changes affect the binary packages:

[The following lists of changes regard files as different if they have different names, permissions or owners.]

Files in second set of .debs but not in first

-rw-r--r--  root/root   /usr/lib/debug/.build-id/c1/a33b6d176f8031733adbfce3d1712661427976.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/6a/dfab04aff8720385dacf1a3d08a374a2bda26e.debug

Control files of package ipe: lines which differ (wdiff format)

• Homepage: [-http​://ipe.otfried.org/-] {+https​://ipe.otfried.org/+}

No differences were encountered between the control files of package **ipe-dbgsym**

Control files of package libipe-dev: lines which differ (wdiff format)

• Homepage: [-http​://ipe.otfried.org/-] {+https​://ipe.otfried.org/+}

Control files of package libipe7.2.26: lines which differ (wdiff format)

• Homepage: [-http​://ipe.otfried.org/-] {+https​://ipe.otfried.org/+}

Control files of package libipe7.2.26-dbgsym: lines which differ (wdiff format)

• Build-Ids: 2f8f0444501ee9a013ea4e5e4c510b22ff84ffe4 44694226ef8e300ac9c03df2124c77c76315e78f 6adfab04aff8720385dacf1a3d08a374a2bda26e a4f1ed4585b6ac0c6813bf2f992cdb1ce63c06f5 c1a33b6d176f8031733adbfce3d1712661427976 f3ccaeb769f6dcf0fd315b4774e908e49f57f054

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