Merge pull request #7 from julian-upc/master

Actualitzar
Merge pull request #2 from julian-upc/master

actualize
Merge pull request #90 from claramateo/master

Sheet1 encrypted
updated sheet 1/2
Sheet2 unencrypted source code
Merge pull request #92 from ideparada/master

Sheet2 unencrypted source code
sheet2_upload

still not finished
New version of Sheet2

Errors corrected, finished 2nd exercise
Merge pull request #94 from elisabetburjons/master

New version Sheet2
Merge pull request #93 from jan-fiser/master

Jan_Fiser_sheet2
added file with plan for example code
modified gitignore
Writing part finish
Merge pull request #96 from pilukno/master

Writing part finish
unencrypted code
added example code from class
Merge remote-tracking branch 'origin/master'
added writing of sheet3
Merge pull request #97 from pilukno/master

unencrypted code
updated running times for Coxeter groups