After pull request #170 c++ document aligner compilation fails with the following error:

[ 44%] Linking CXX executable bin/ngram_test
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/Scrt1.o: in function `_start':
(.text+0x24): undefined reference to `main'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/ngram_test.dir/build.make:163: bin/ngram_t

The urls used in the code and documentation should be checked for availability (As done for the readme in #87)

Places to check:

• URLs in the CorpusDownloader classes
• URLs in the code-doc of CorpusReader classes

Feature just like "Suggest" in PML-TQ web, which allows a user to pick nodes in a tree in search results (words in a concordance line, in case of Kontext), visualise the nodes (words) with all their attributes and pick the ones that should be part of the new query.

See e.g. http://hdl.handle.net/11346/PMLTQ-ELDJ, execute the query and click on some nodes in a resulting tree. Suggest button w

For corpus documentation issues it would be great to print the applied annotations (key + value, annotation concept). Thus, the corpus annotators can easily build the corpus annotation guidelines.

Is your feature request related to a problem?
The Menu and Help List need to be updated to reflect current functions
.
Describe the solution you'd like

1. The Menu and Help should show the following:

• Name (one-word name of function)
• Key (keyboard shortcut)
• Description (brief description of the function, displayed only when the user hovers)

2. Where possible, standard keyst